explain xkcd - User contributions [en]

2048: Curve-Fitting

2018-09-19T19:55:06Z

Cvtsi2sd: Some more on ad-hoc filter

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, they may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

**The logarithmic and exponential interpretations could very easily be fudged or engineered by a researcher with an agenda (such as by taking a misleading subset or even outright lieing about the regression), which the comic mocks by juxtaposing them side-by-side on the same set of data.

* LOESS: <math>w(x) = (1-|d|^3)^3</math> (notice: this is just the function used for the weights, not the actually fitted curve formula, as it's a piecewise polynomial) A LOESS fit doesn't use a single formula to fit all the data, but approximates data points locally using different polynomials for each "zone" (weighting differently data points as they get further from it) and patching them togetherAs it has much more degrees of freedom compared to a single polynomial, it generally "fits better" to any data set, although it is generally impossible to derive any strong, "clean" mathematical correlation from it - it is just a nice smooth line that approximates well the data points, with a good degree of rejection from outliers.

* Linear, No Slope: <math>f(x) = c</math> Apparently, the person making this line figured out pretty early on that their data analysis was turning into a scatter plot, and wanted to escape their personal stigma of scatter plots by drawing an obviously false regression line on top of it. Alternatively, they were hoping the data would be flat, and are trying to pretend that there's no real trend to the data by drawing a horizontal trend line.

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math> A logistic curve provides a smooth, S-shaped transition curve between two flat intervals; indeed the caption says that the experimenter just wants to find a mathematically-respectable way to link two flat lines.

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve. Providing a confidence interval over the graph shows the uncertainty of the acquired data, thus acknowledging the uncertain results of the experiment, and showing the will not to "cheat" with "easy" regression curves.

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand, keeping in only the data points perceived as "good". Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of ''overfitting''.

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

Since so many different models can fit this data set at first glance, Randall may be making a point about how if a data set is sufficiently messy, you can read any trend you want into it, and the trend that is chosen may say more about the researcher than about the data.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:LOESS
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:50:24Z

Cvtsi2sd: Added explanation about confidence interval

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, they may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

**The logarithmic and exponential interpretations could very easily be fudged or engineered by a researcher with an agenda (such as by taking a misleading subset or even outright lieing about the regression), which the comic mocks by juxtaposing them side-by-side on the same set of data.

* LOESS: <math>w(x) = (1-|d|^3)^3</math> (notice: this is just the function used for the weights, not the actually fitted curve formula, as it's a piecewise polynomial) A LOESS fit doesn't use a single formula to fit all the data, but approximates data points locally using different polynomials for each "zone" (weighting differently data points as they get further from it) and patching them togetherAs it has much more degrees of freedom compared to a single polynomial, it generally "fits better" to any data set, although it is generally impossible to derive any strong, "clean" mathematical correlation from it - it is just a nice smooth line that approximates well the data points, with a good degree of rejection from outliers.

* Linear, No Slope: <math>f(x) = c</math> Apparently, the person making this line figured out pretty early on that their data analysis was turning into a scatter plot, and wanted to escape their personal stigma of scatter plots by drawing an obviously false regression line on top of it. Alternatively, they were hoping the data would be flat, and are trying to pretend that there's no real trend to the data by drawing a horizontal trend line.

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math> A logistic curve provides a smooth, S-shaped transition curve between two flat intervals; indeed the caption says that the experimenter just wants to find a mathematically-respectable way to link two flat lines.

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve. Providing a confidence interval over the graph shows the uncertainty of the acquired data, thus acknowledging the uncertain results of the experiment, and showing the will not to "cheat" with "easy" regression curves.

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of ''overfitting''.

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

Since so many different models can fit this data set at first glance, Randall may be making a point about how if a data set is sufficiently messy, you can read any trend you want into it, and the trend that is chosen may say more about the researcher than about the data.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:LOESS
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:46:10Z

Cvtsi2sd: Added explanation about the logistic regression

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, they may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

**The logarithmic and exponential interpretations could very easily be fudged or engineered by a researcher with an agenda (such as by taking a misleading subset or even outright lieing about the regression), which the comic mocks by juxtaposing them side-by-side on the same set of data.

* LOESS: <math>w(x) = (1-|d|^3)^3</math> (notice: this is just the function used for the weights, not the actually fitted curve formula, as it's a piecewise polynomial) A LOESS fit doesn't use a single formula to fit all the data, but approximates data points locally using different polynomials for each "zone" (weighting differently data points as they get further from it) and patching them togetherAs it has much more degrees of freedom compared to a single polynomial, it generally "fits better" to any data set, although it is generally impossible to derive any strong, "clean" mathematical correlation from it - it is just a nice smooth line that approximates well the data points, with a good degree of rejection from outliers.

* Linear, No Slope: <math>f(x) = c</math> Apparently, the person making this line figured out pretty early on that their data analysis was turning into a scatter plot, and wanted to escape their personal stigma of scatter plots by drawing an obviously false regression line on top of it. Alternatively, they were hoping the data would be flat, and are trying to pretend that there's no real trend to the data by drawing a horizontal trend line.

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math> A logistic curve provides a smooth, S-shaped transition curve between two flat intervals; indeed the caption says that the experimenter just wants to find a mathematically-respectable way to link two flat lines.

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve.

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of ''overfitting''.

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

Since so many different models can fit this data set at first glance, Randall may be making a point about how if a data set is sufficiently messy, you can read any trend you want into it, and the trend that is chosen may say more about the researcher than about the data.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:LOESS
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:43:46Z

Cvtsi2sd: Fixed capitalization of LOESS

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, they may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

**The logarithmic and exponential interpretations could very easily be fudged or engineered by a researcher with an agenda (such as by taking a misleading subset or even outright lieing about the regression), which the comic mocks by juxtaposing them side-by-side on the same set of data.

* LOESS: <math>w(x) = (1-|d|^3)^3</math> (notice: this is just the function used for the weights, not the actually fitted curve formula, as it's a piecewise polynomial) A LOESS fit doesn't use a single formula to fit all the data, but approximates data points locally using different polynomials for each "zone" (weighting differently data points as they get further from it) and patching them togetherAs it has much more degrees of freedom compared to a single polynomial, it generally "fits better" to any data set, although it is generally impossible to derive any strong, "clean" mathematical correlation from it - it is just a nice smooth line that approximates well the data points, with a good degree of rejection from outliers.

* Linear, No Slope: <math>f(x) = c</math> Apparently, the person making this line figured out pretty early on that their data analysis was turning into a scatter plot, and wanted to escape their personal stigma of scatter plots by drawing an obviously false regression line on top of it. Alternatively, they were hoping the data would be flat, and are trying to pretend that there's no real trend to the data by drawing a horizontal trend line.

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math>

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve.

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of ''overfitting''.

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

Since so many different models can fit this data set at first glance, Randall may be making a point about how if a data set is sufficiently messy, you can read any trend you want into it, and the trend that is chosen may say more about the researcher than about the data.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:LOESS
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:42:33Z

Cvtsi2sd: Added explanation about the LOESS regression

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, they may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

**The logarithmic and exponential interpretations could very easily be fudged or engineered by a researcher with an agenda (such as by taking a misleading subset or even outright lieing about the regression), which the comic mocks by juxtaposing them side-by-side on the same set of data.

* LOESS: <math>w(x) = (1-|d|^3)^3</math> (notice: this is just the function used for the weights, not the actually fitted curve formula, as it's a piecewise polynomial) A Loess fit doesn't use a single formula to fit all the data, but approximates data points locally using different polynomials for each "zone" (weighting differently data points as they get further from it) and patching them togetherAs it has much more degrees of freedom compared to a single polynomial, it generally "fits better" to any data set, although it is generally impossible to derive any strong, "clean" mathematical correlation from it - it is just a nice smooth line that approximates well the data points, with a good degree of rejection from outliers.

* Linear, No Slope: <math>f(x) = c</math> Apparently, the person making this line figured out pretty early on that their data analysis was turning into a scatter plot, and wanted to escape their personal stigma of scatter plots by drawing an obviously false regression line on top of it. Alternatively, they couldn't be bothered to learn how to properly use their graphics program, and just selected the first trend line it offered them.

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math>

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve.

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of ''overfitting''.

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

Since so many different models can fit this data set at first glance, Randall may be making a point about how if a data set is sufficiently messy, you can read any trend you want into it, and the trend that is chosen may say more about the researcher than about the data.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:Loess
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:28:11Z

Cvtsi2sd: Missing in previous edit

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, it may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

* Loess: <math>w(x) = (1-|d|^3)^3</math>

* Linear, No Slope: <math>f(x) = c</math>

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math>

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of _overfitting_

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:Loess
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:27:36Z

Cvtsi2sd: Added explanation about the exponential regression

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question. Here we see various hypothetical scientists or statisticians each applying their own interpretations, and the comic mocks each of them for their various personal biases or other assorted excuses.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, it may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math> An exponential curve, on the contrary, is typical of a phenomenon whose growth gets rapidly faster and faster - a common case is a process that generates stuff that contributes to the process itself, think bacteria growth or composite interest.

* Loess: <math>w(x) = (1-|d|^3)^3</math>

* Linear, No Slope: <math>f(x) = c</math>

* Logistic: <math>f(x) = L / (1 + e^{-k(x-b)})</math>

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of _overfitting_

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:Loess
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:23:22Z

Cvtsi2sd: Added explanation about the logarithmic fit

{{comic
| number = 2048
| date = September 19, 2018
| title = Curve-Fitting
| image = curve_fitting.png
| titletext = Cauchy-Lorentz: "Something alarmingly mathematical is happening, and you should probably pause to Google my name and check what field I originally worked in."
}}

==Explanation==
{{incomplete|Created by a HOUSE OF CARDS: Please edit the explanation below and only mention here why it isn't complete. Do NOT delete this tag too soon.}}

A illustration of several plots of the same data with curves fitted to the points, paired with conclusions that you might draw about the person who made them.

When modeling a phenomenon statistically, it is common to search for trends, and fitted curves can help reveal these trends. Much of the work of a data scientist or statistician is knowing which fitting method to use for the data in question.

In general, the researcher will specify the form of an equation for the line to be drawn, and an algorithm will produce the actual line.

This comic is similar to [[977: Map Projections]] which also uses a scientific method not commonly thought about by the general public to determine specific characteristics of one's personality and approach to science.

* Linear: <math>f(x) = mx + b</math> Linear regression is the most basic form of regression; it tries to find the straight line that best approximates the data.As it's the simplest, most widely taught form of regression, and in general derivable function are locally well approximated by a straight line, it's usually the first and most trivial attempt of fit.

* Quadratic: <math>f(x) = ax^2 + bx + c</math> Quadratic fit (i.e. fitting a parabola through the data) is the lowest grade polynomial that can be used to fit data through a curved line; if the data exhibits clearly "curved" behavior (or if the experimenter feels that its growth should be more than linear), a parabola is often the first stab at fitting the data.

* Logarithmic: <math>f(x) = a*\log_b(x) + c</math> A logarithmic curve is typical of a phenomenon whose growth gets slower and slower as time passes (indeed, its derivative - i.e. its growth rate - is <math>\propto \frac{1}{x} \rightarrow 0</math> for <math>x \rightarrow +\infty</math>); if the experimenter wants to find confirmation of this fact, it may try to fit a logarithmic curve.

* Exponential: <math>f(x) = a*b^x + c</math>

* Loess: <math>w(x) = (1-|d|^3)^3</math>

* Linear, No Slope: <math>f(x) = c</math>

* Logistic: <math>f(x) = L / (1 + e^(-k(x-b)))</math>

* Confidence Interval: not a type of curve fitting, but a method of depicting the predictive power of a curve

* Piecewise: Mapping different curves to different segments of the data. This is a legitimate strategy, but the different segments should be meaningful, such as if they were pulled from different populations.

* Connecting lines: Not useful whatsoever, but it looks nice!

* Ad-Hoc Filter: Drawing a bunch of different lines by hand. Also not useful.

* House of Cards: Not a real method, but a common consequence of mis-application of statistical methods: a curve can be generated that fits the data extremely well, but immediately becomes absurd as soon as one glances outside the training data sample range, and your analysis comes crashing down "like a house of cards". This is a type of _overfitting_

* Cauchy-Lorentz: Is a continuous probability distribution which does not have an expected value or a defined variance. This means that the law of large numbers does not hold and that estimating e.g. the sample mean will diverge (be all over the place) the more data points you have. Hence very troublesome (mathematically alarming). See https://en.wikipedia.org/wiki/Cauchy_distribution

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}
:'''Curve-Fitting Methods'''
:and the messages they send

:[In a single frame twelve scatter plots with unlabeled x- and y-axes are shown. Each plot consists of the same data-set of approximately thirty points located all over the plot but slightly more distributed around the diagonal. Every plot shows in red a different fitting method which is labeled on top in gray.]

:[The first plot shows a line starting at the left bottom above the x-axis rising towards the points to the right.]
:Linear
:"Hey, I did a regression."

:[The second plot shows a curve falling slightly down and then rising up to the right.]
:Quadratic
:"I wanted a curved line, so I made one with Math."

:[At the third plot the curve starts near the left bottom and increases more and more less to the right.]
:Logarithmic
:"Look, it's tapering off!"

:[The fourth plot shows a curve starting near the left bottom and increases more and more steeper to the right.]
:Exponential
:"Look, it's growing uncontrollably!"

:[The fifth plot uses a fitting to match many points. It starts at the left bottom, increases, then decreases, then rapidly increasing again, and finally reaching a plateau.]
:Loess
:"I'm sophisticated, not like those bumbling polynomial people."

:[The sixth plot simply shows a line above but parallel to the x-axis.]
:Linear, no slope
:"I'm making a scatter plot but I don't want to."

:[At plot #7 starts at a plateau above the x-axis, then increases, and finally reaches a higher plateau.]
:Logistic
:"I need to connect these two lines, but my first idea didn't have enough Math."

:[Plot #8 shows two red lines embedding most points and the area between is painted as a red shadow.]
:Confidence interval
:"Listen, science is hard. But I'm a serious person doing my best."

:[Plot #9 shows two not connected lines, one at the lower left half, and one higher at the right. Both have smaller curved lines in light red above and below.]
:Piecewise
:"I have a theory, and this is the only data I could find."

:[The plot at the left bottom shows a line connecting all points from left to right, resulting in a curve going many times up and down.]
:Connecting lines
:"I clicked 'Smooth Lines' in Excel."

:[The next to last plot shows a echelon form, connecting a few real and some imaginary points.]
:Ad-Hoc filter
:"I had an idea for how to clean up the data. What do you think?"

:[The last plot shows a wave with increasing peak values.]
:House of Cards
:"As you can see, this model smoothly fits the- ''wait no no don't extend it AAAAAA!!''"

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Scatter plots]]
[[Category:Math]]
[[Category:Science]]

2048: Curve-Fitting

2018-09-19T19:15:00Z

Cvtsi2sd: Use math for formulas

2048: Curve-Fitting

2018-09-19T19:12:50Z

Cvtsi2sd: Added explanation about the quadratic regression

2048: Curve-Fitting

2018-09-19T19:09:41Z

Cvtsi2sd: Added explanation about the linear regression

1975: Right Click

2018-04-02T18:00:30Z

Cvtsi2sd: aptitude != apt

{{comic
| number = 1975
| date = April 1, 2018
| title = Right Click
| image = right_click.png
| titletext = "Right-click or long press (where supported) to save!"
}}
'''NOTE: The above is the first panel of an interactive comic.''' 
To experience the interactive content, click [https://www.xkcd.com/1975/ here].

==Explanation==
{{incomplete|Please add an explanation table of all functions This is an April Fools comic, so it'll take a while to get organised and much longer to fill out. Do NOT delete this tag too soon.}}

This is an interactive comic which manipulates the context menu of the browser. This menu is typically accessible by a right-click or a long press on mobile devices without a mouse.

The comic uses {{w|Javascript}} and {{w|HTML5}} to override the standard context menu. Since modern browsers use the same features to integrate Add-ons into that menu, the behaviour may be different depending on the browser environment.

The manipulated context menu is described below:
;Main Context Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! # !! Menu Item !! Explanation !! Sub-Menu Items
|-
!1
| '''Save'''
| Only appears after successfully completing the ADVENT.EXE game or getting the easter egg in mornington crescent.
| Save image> Downloads this image. [https://xkcd.com/1975/v6xso1_right_click_save.png]

|-
! 2
| '''File'''
| Normal submenu
|Close> Closes menu, does nothing.
Open: A:\, C:\, / (See more [[#Table - Filesystems Menu|below]])

Find: Where, When, How, (not usable) What, Why

|-
! 3
| '''Edit'''
| Enables a mode allowing the user to draw on the webpage. Pressing Esc asks "Aw, that looks nice though. Really delete?" and the page returns to normal if OK is clicked.
| None
|-
! 4
| '''System'''
| Normal submenu
|Shut Down> Changes the only menu option to "Power on", then once that is used, system returns to normal.

/ (See [[#Table - Filesystems Menu|below]])
|-
! 5
| '''View'''
| Normal submenu
|Cascade>Links to [http://wiki.xkcd.com/geohashing/Mt._St._Helens,_Washington]

Tile> Links to [[245: Floor Tiles]]

Minimize> Changes pointer to a smaller pointer.

Full Screen> Enters full screen.
|-
! 6
| '''Utilities'''
| Normal submenu
|Park drives> Nothing.

Check space usage> (cannot click) Space usage: -Dark matter -Hydrogen -Helium -Scattered clumps of heavier elements -Stars -Rocks -Some space probes -Earth

Spell check> English (links to [[1069: Alphabet]]) and Colors (links to [https://blog.xkcd.com/2010/05/03/color-survey-results/])

Train AI> links to [[1838: Machine Learning]]

Identify song> opens a long word-by-word menu for song lyrics; it's actually a menu-ised version of [[851: Na]].

Advanced> several Unix commands, all absurd (or dangerous) for some reason:
* <code>apt-get install /dev/null</code>: <code>apt-get</code> is the standard package manager used in Debian-derived Linux distributions (including Ubuntu); it is normally used to install software; <code>/dev/null</code> is the "bit-bucket" device on any Unix system, which can be used as a dummy output file to discard output or as a dummy empty input file. This command would attempt to install <code>/dev/null</code> (which is a device, not a package!) or, more correctly, would try to install a package reading its data from <code>/dev/null</code> (if <code>apt-get</code> is given a file name it tries to interpret it as a .deb package), which is obviously impossible.
* <code>brew install apt-get</code>: <code>brew</code> is a third-party package manager for macOS; it is generally used to install "missing" open-source utilities on a macOS system; the command is attempting to install the aforementioned <code>apt-get</code>, which is both impossible (<code>apt-get</code> doesn't run on macOS) and hilariously recursive (did you install a package manager - brew - to install another one?). Even if this were possible, the package would have been called <code>apt</code>, as apt-get is only one of the commands in the package manager.
* <code>/usr/local/bin/wine xen-hypervisor.exe</code>: <code>wine</code> is a compatibility layer used to run Windows executables on Linux (and on macOS); the fact that it is in <code>/usr/local</code> hints that it has been manually compiled on this machine; Xen is a Linux-based hypervisor, i.e. a software used to run and manage virtual machines over a Linux host, but the .exe suffix here hints that it is a Windows executable. The command would try to launch a Windows build of a Linux-based virtual machine manager on a Unix machine through a Windows emulation layer (wine).
* <code>source .bash_history</code>: the <code>source</code> shell command reads the file that is given as argument and executes each of its rows as a command in the current shell, roughly as if you typed them in; <code>.bash_history</code> (located in the user home directory) is the file where the bash shell saves the history of the commands that have been run. This command would re-run all the command that have been typed in the shell.
* <code>rm -rf $DIRECTROY/*</code>: <code>rm -rf</code> deletes recursively and forcefully the paths it is given as arguments; <code>$DIRECTROY</code> is a shell variable, probably containing some directory that whoever typed in this command wanted to clean; however, it is misspelled (it says <code>$DIRECTROY</code>, not <code>$DIRECTORY</code>), and, due to how POSIX shell work, it is thus expanded to an empty string; so, the command becomes <code>rm -rf /*</code>, which deletes all the files and directories in the root of the disk, effectively killing the system instead of just deleting the content of some directory. Notice that this particular misspell manages to circumvent the builtin protection of many <code>rm</code> versions, which refuse to do a plain <code>rm -rf /</code>, as <code>/*</code> gets expanded by the shell, so <code>rm</code> never has the chance to see explicitly that you are killing all the data in the root directory.
* <code>:(){:|:&};:</code>: this is [https://askubuntu.com/q/159491/208527 a classic shell fork bomb], i.e. a small program that keeps launching copies of itself, until all resources have been exhausted or the user somehow manages to kill all its copies.
* <code>echo "source .bashrc" >> .bashrc</code>: <code>.bashrc</code> is a file that gets executed whenever the <code>bash</code> shell is started in interactive mode; this command appends the string <code>source .bashrc</code> to it, which effectively executes it again recursively; this would pretty much make it impossible to open an interactive shell when launching it with the default parameters.
* <code>alias gcc=php</code>: the <code>alias</code> shell builtin create an alias for another command; <code>gcc</code> is the GNU C compiler driver, which is used to compile programs written in the C language; <code>php</code> is the command-line interpreter for the PHP language. This line creates an alias such that when typing <code>gcc</code>, <code>php</code> is actually invoked, which would generate completely absurd error messages. This is doubly devious, as PHP isn't generally held in high esteem by large part of the programming community (especially by someone writing stuff in C).

'); DROP TABLE Menus;-- links to [[327: Exploits of a Mom]]
|-
! 7
| '''Games'''
| Normal submenu
| Twenty Questions> A Twenty Questions interface that gets really confusing.

Rock Paper Scissors> A Rock Paper Scissors game where the computer always matches your move.

D&D> A complex Dungeons and Dragons interface. Allows you to cast various spells from D&D 5e which link to various pages, including xkcd comics (e.g. [[1331: Frequency]]), what-ifs (e.g. {{what if|144|Saliva Pool}}) and other external sites (e.g. [https://www.nasa.gov/sun The Sun | NASA]).

ADVENT.EXE> A text-based game. If played correctly, you can win, unlocking 'Save'>'Save image' from the beginning menu, which links to [https://xkcd.com/1975/v6xso1_right_click_save.png]. 'ADVENT.EXE>Castle>Well>Wish for...' has links to comics [[572: Together]], [[1053: Ten Thousand]], [[152: Hamster Ball]], [[1196: Subways]], [[231: Cat Proximity]] and to what-if articles {{what if|111|All the Money}} and {{what if|9|Soul Mates}}.

Hoverboard> Links to [[1608: Hoverboard]].

Mornington Crescent> This is a simulation of the well-known game {{W|Mornington_Crescent_(game)|Mornington Crescent}}, which bears a surprising resemblance to {{W|London_Underground|London's Underground}} railway network. Players name a station, in turn, endeavouring to reach Mornington Crescent. The rules of play are very complicated and beyond the scope of this article; interested persons are referred to ''N. F. Stovold’s Mornington Crescent: Rules and Origins'' (sadly out of print). In this variation, one may reach 'Vauxhall'>'Easter basket'>'Take egg', also allowing you to save.
|-
! 8
| '''Help'''
| Contains various submenus, all of which, barring Credits, loop back recursively to this menu:
|Tutorial
Support

Manual

Troubleshooting

FAQ

Guide

Q&A

User forums

--------------

Credits> 'Some people who helped with this comic:
[http://chromakode.com/ @chromakode]
[https://twitter.com/aiiane Amber]
[https://twitter.com/fadinginterest @fadinginterest]
[https://twitter.com/wirehead2501 Kat]
[https://twitter.com/cotrone Kevin]
[http://90d.ca/ Stereo]'
|-
! 9
| '''Do Crimes'''
| Contains several "crimes" that can be committed. This option is unlocked by File > Open > C:\ (or /home/user) > Bookmarks/ > Secret > Enable Dark Web.
| Steal Bitcoins > Grayed out.
Say swears > Several clean swears that all link to [[771: Period Speech]].

Hack > Three sub-options that link to various related comics. (Gibson: Nothing. Election: [[1019: First Post]]. Planet: [[1337: Hack]].)

Forge a Scrabble Tile > Several sub-options that don't do anything. (U, Z, <this menu option intentionally left blank>, and two special characters, one appearing like a reversed 'E' modelled on a 'C', or Russian 'Э', as low-pitched [eh], and the second being crossed swords)
|}

;Filesystems Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! Drive !! Menu Item !! Explanation !! Sub-Menu Items
|-
! A:\
| '''Insert'''
| Only appears before inserting a floppy disk.
|Floppy disk> Unlocks other options for drive A:\, which are identical to drive C:\
Chip card> A long sequence of being told 'Please wait. Authorizing...' ending in 'Chip error! REMOVE CARD NOW!'
|-
! C:\
| '''Documents/'''
| Nothing.
| None.
|-
! C:\
| '''Music/'''
| Leads to a long string of prompts for song lyrics, same as 'Hey now / Hey now na now / Sing "This Corrosion" to me' inverts the webpage's color. It's actually the same menu that is shown under Utilities>Identify song (which itself is a menu-ised version of [[851: Na]]).
|-
! C:\
| '''Bookmarks/'''
| Similar to Music/, Bookmarks/> Comics leads to a chain from which many comics are titled and linked. Bookmarks/> Secret> Enable Dark Web adds the 'Dark Web' option to the initial menu.
|-
! C:\
| '''Games/'''
| Same as 'Games' from the initial menu.
|-
! C:\
| '''Sequences/'''
| The options are the lines from a ''Tim and Eric'' sketch [http://knowyourmeme.com/memes/celery-man Celery Man]; the final option links to a YouTube video of the sketch.
| After several single-option menus, it links to this Youtube video. https://www.youtube.com/watch?v=MHWBEK8w_YY
|-
! /
| '''home/'''
| Nothing.
| guest> links to [//uni.xkcd.com]

user> Same files as C:\

root> Displays 'You are not in the sudoers file. This incident will be reported.'
|-
! /
| '''opt/'''
| Does nothing.
| None.
|-
! /
| '''sbin/'''
| Does nothing.
| None.
|-
! /
| '''usr/'''
| Opens an infinite sequence of options, each similar to the last, but replacing the previous selection with another folder; probably a reference to the fact that [https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/usr.html the /usr hierarchy] does contain a list of subdirectories pretty much identical [https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/the-root-directory.html to those of the root directory].
|-
! /
| '''dev/'''
| Nothing.
|random/> links to a random xkcd comic.
urandom/> links to [[221: Random Number]]
|}

In an additional fool it introduces the [https://uni.xkcd.com/ Unix XKCD] as a reference to the {{W|Telenet}}. (More on UniXKCD commands can be found [[721:_Flatland#UniXKCD|here]].)

==Transcript==
:[Empty frame with Cueball slightly right of centre.]

:[Caption below the frame:]
:Editor's Note: Today's comic is optimized for local viewing. To see the full version, just save a copy of the image!

{{comic discussion}}



[[Category:Interactive comics]]
[[Category:April fools' comics]]

1975: Right Click

2018-04-02T16:44:01Z

Cvtsi2sd: c:\Music is actually the same as Utilities>Identify song

{{comic
| number = 1975
| date = April 1, 2018
| title = Right Click
| image = right_click.png
| titletext = "Right-click or long press (where supported) to save!"
}}
'''NOTE: The above is the first panel of an interactive comic.''' 
To experience the interactive content, click [https://www.xkcd.com/1975/ here] or this link for [https://m.xkcd.com/1975/ mobile devices].

==Explanation==
{{incomplete|Please add an explanation table of all functions This is an April Fools comic, so it'll take a while to get organized and much longer to fill out. Do NOT delete this tag too soon.}}

This is an interactive comic which manipulates the context menu of the browser. This menu is typically accessible by a right-click or a long press on mobile devices without a mouse.

The comic uses {{w|Javascript}} and {{w|HTML5}} to override the standard context menu. Since modern browsers use the same features to integrate Add-ons into that menu the behave may be different depending on the browser environment.

The manipulated context menu is described below:
;Main Context Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! # !! Menu Item !! Explanation !! Sub-Menu Items
|-
!1
| '''Save'''
| Only appears after successfully completing the ADVENT.EXE game or getting the easter egg in mornington crescent.
| Save image> Downloads this image. [https://xkcd.com/1975/v6xso1_right_click_save.png]

|-
! 2
| '''File'''
| Normal submenu
|Close> Closes menu, does nothing.
Open: A:\, C:\, / (See more [[#Table - Filesystems Menu|below]])

Find: Where, When, How, (not usable) What, Why

|-
! 3
| '''Edit'''
| Enables a mode allowing the user to draw on the webpage. Pressing Esc asks "Aw, that looks nice though. Really delete?" and the page returns to normal if OK is clicked.
| None
|-
! 4
| '''System'''
| Normal submenu
|Shut Down> Changes the only menu option to "Power on", then once that is used, system returns to normal.

/ (See [[#Table - Filesystems Menu|below]])
|-
! 5
| '''View'''
| Normal submenu
|Cascade>Links to [http://wiki.xkcd.com/geohashing/Mt._St._Helens,_Washington]

Tile> Links to [[245: Floor Tiles]]

Minimize> Changes pointer to a smaller pointer.

Full Screen> Enters full screen.
|-
! 6
| '''Utilities'''
| Normal submenu
|Park drives> Nothing.

Check space usage> (cannot click) Space usage: -Dark matter -Hydrogen -Helium -Scattered clumps of heavier elements -Stars -Rocks -Some space probes -Earth

Spell check> English (links to [[1069: Alphabet]]) and Colors (links to [https://blog.xkcd.com/2010/05/03/color-survey-results/])

Train AI> links to [[1838: Machine Learning]]

Identify song> opens a long word-by-word menu for song lyrics; it's actually a menu-ized version of [[851: Na]].

Advanced> several Unix commands, all absurd (or dangerous) for some reason:
* <code>apt-get install /dev/null</code>: <code>apt-get</code> is the standard package manager used in Debian-derived Linux distributions (including Ubuntu); it is normally used to install software; <code>/dev/null</code> is the "bit-bucket" device on any Unix system, which can be used as a dummy output file to discard output or as a dummy empty input file. This command would attempt to install <code>/dev/null</code> (which is a device, not a package!) or, more correctly, would try to install a package reading its data from <code>/dev/null</code> (if <code>apt-get</code> is given a file name it tries to interpret it as a .deb package), which is obviously impossible.
* <code>brew install apt-get</code>: <code>brew</code> is a third-party package manager for macOS; it is generally used to install "missing" open-source utilities on a macOS system; the command is attempting to install the aforementioned <code>apt-get</code>, which is both impossible (<code>apt-get</code> doesn't run on macOS) and hilariously recursive (did you install a package manager - brew - to install another one?)
* <code>/usr/local/bin/wine xen-hypervisor.exe</code>: <code>wine</code> is a compatibility layer used to run Windows executables on Linux (and on macOS); the fact that it is in <code>/usr/local</code> hints that it has been manually compiled on this machine; Xen is a Linux-based hypervisor, i.e. a software used to run and manage virtual machines over a Linux host, but the .exe suffix here hints that it is a Windows executable. The command would try to launch a Windows build of a Linux-based virtual machine manager on a Unix machine through a Windows emulation layer (wine).
* <code>source .bash_history</code>: the <code>source</code> shell command reads the file that is given as argument and executes each of its rows as a command in the current shell, roughly as if you typed them in; <code>.bash_history</code> (located in the user home directory) is the file where the bash shell saves the history of the commands that have been run. This command would re-run all the command that have been typed in the shell.
* <code>rm -rf $DIRECTROY/*</code>: <code>rm -rf</code> deletes recursively and forcefully the paths it is given as arguments; <code>$DIRECTROY</code> is a shell variable, probably containing some directory that whoever typed in this command wanted to clean; however, it is misspelled (it says <code>$DIRECTROY</code>, not <code>$DIRECTORY</code>), and, due to how POSIX shell work, it is thus expanded to an empty string; so, the command becomes <code>rm -rf /*</code>, which deletes all the files and directories in the root of the disk, effectively killing the system instead of just deleting the content of some directory. Notice that this particular misspell manages to circumvent the builtin protection of many <code>rm</code> versions, which refuse to do a plain <code>rm -rf /</code>, as <code>/*</code> gets expanded by the shell, so <code>rm</code> never has the chance to see explicitly that you are killing all the data in the root directory.
* <code>:(){:|:&};:</code>: this is [https://askubuntu.com/q/159491/208527 a classic shell fork bomb], i.e. a small program that keeps launching copies of itself, until all resources have been exhausted or the user somehow manages to kill all its copies.
* <code>echo "source .bashrc" >> .bashrc</code>: <code>.bashrc</code> is a file that gets executed whenever the <code>bash</code> shell is started in interactive mode; this command appends the string <code>source .bashrc</code> to it, which effectively executes it again recursively; this would pretty much make it impossible to open an interactive shell when launching it with the default parameters.
* <code>alias gcc=php</code>: the <code>alias</code> shell builtin create an alias for another command; <code>gcc</code> is the GNU C compiler driver, which is used to compile programs written in the C language; <code>php</code> is the command-line interpreter for the PHP language. This line creates an alias such that when typing <code>gcc</code>, <code>php</code> is actually invoked, which would generate completely absurd error messages. This is doubly devious, as PHP isn't generally held in high esteem by large part of the programming community (especially by someone writing stuff in C).

'); DROP TABLE Menus;-- links to [[327: Exploits of a Mom]]
|-
! 7
| '''Games'''
| Normal submenu
| Twenty Questions> A Twenty Questions interface that gets really confusing.

Rock Paper Scissors> A Rock Paper Scissors game where the computer always matches your move.

D&D> A complex Dungeons and Dragons interface. Allows you to cast various spells from D&D 5e which link to various pages, including xkcd comics (e.g. [[1331: Frequency]]), what-ifs (e.g. {{what if|144|Saliva Pool}}) and other external sites (e.g. [https://www.nasa.gov/sun The Sun | NASA]).

ADVENT.EXE> A text-based game. If played correctly, you can win, unlocking 'Save'>'Save image' from the beginning menu, which links to [https://xkcd.com/1975/v6xso1_right_click_save.png]. 'ADVENT.EXE>Castle>Well>Wish for...' has links to comics [[572: Together]], [[1053: Ten Thousand]], [[152: Hamster Ball]], [[1196: Subways]], [[231: Cat Proximity]] and to what-if articles {{what if|111|All the Money}} and {{what if|9|Soul Mates}}.

Hoverboard> Links to [[1608: Hoverboard]].

Mornington Crescent> This is a simulation of the well-known game [https://en.wikipedia.org/wiki/Mornington_Crescent_(game) Mornington Crescent], which bears a surprising resemblance to London's [https://en.wikipedia.org/wiki/London_Underground Underground] railway network. Players name a station in turn, endeavouring to reach Mornington Crescent. The rules of play are very complicted and beyond the scope of this article; interested persons are referred to ''N. F. Stovold’s Mornington Crescent: Rules and Origins'' (sadly out of print). In this variation, one may reach 'Vauxhaull'>'Easter basket'>'Take egg', also allowing you to save.
|-
! 8
| '''Help'''
| Contains various submenus, all of which, barring Credits, loop back recursively to this menu:
|Tutorial
Support

Manual

Troubleshooting

FAQ

Guide

Q&A

User forums

--------------

Credits> 'Some people who helped with this comic:
[http://chromakode.com/ @chromakode]
[https://twitter.com/aiiane Amber]
[https://twitter.com/fadinginterest @fadinginterest]
[https://twitter.com/wirehead2501 Kat]
[https://twitter.com/cotrone Kevin]
[http://90d.ca/ Stereo]'
|-
! 9
| '''Do Crimes'''
| Contains several "crimes" that can be committed. This option is unlocked by File > Open > C:\ (or /home/user) > Bookmarks/ > Secret > Enable Dark Web.
| Steal Bitcoins > Grayed out.
Say swears > Several clean swears that all link to [[771: Period Speech]].

Hack > Three sub-options that link to various related comics. (Gibson: Nothing. Election: [[1019: First Post]]. Planet: [[1337: Hack]].)

Forge a Scrabble Tile > Several sub-options that don't do anything. (U, Z, <this menu option intentionally left blank>, and two special characters, one appearing like a reversed 'E' modeled on a 'C', or Russian 'Э', as low-pitched [eh], and the second being crossed swords)
|}

;Filesystems Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! Drive !! Menu Item !! Explanation !! Sub-Menu Items
|-
! A:\
| '''Insert'''
| Only appears before inserting a floppy disk.
|Floppy disk> Unlocks other options for drive A:\, which are identical to drive C:\
Chip card> A long sequence of being told 'Please wait. Authorizing...' ending in 'Chip error! REMOVE CARD NOW!'
|-
! C:\
| '''Documents/'''
| Nothing.
| None.
|-
! C:\
| '''Music/'''
| Leads into a long string of prompts for song lyrics, same as 'Hey now / Hey now na now / Sing "This Corrosion" to me' inverts the webpage's color. It's actually the same menu that is shown under Utilities>Identify song (which itself is a menu-ized version of [[851: Na]]).
|-
! C:\
| '''Bookmarks/'''
| Similar to Music/, Bookmarks/> Comics leads to a chain from which many comics are titled and linked. Bookmarks/> Secret> Enable Dark Web adds the 'Dark Web' option to the initial menu.
|-
! C:\
| '''Games/'''
| Same as 'Games' from the initial menu.
|-
! C:\
| '''Sequences/'''
| The options are the lines from a ''Tim and Eric'' sketch [http://knowyourmeme.com/memes/celery-man Celery Man]; the final option links to a YouTube video of the sketch.
| After several single-option menus, it links to this Youtube video. https://www.youtube.com/watch?v=MHWBEK8w_YY
|-
! /
| '''home/'''
| Nothing.
| guest> links to [//uni.xkcd.com]

user> Same files as C:\

root> Displays 'You are not in the sudoers file. This incident will be reported.'
|-
! /
| '''opt/'''
| Does nothing.
| None.
|-
! /
| '''sbin/'''
| Does nothing.
| None.
|-
! /
| '''usr/'''
| Opens an infinite sequence of options, each similar to the last, but replacing the previous selection with another folder; probably a reference to the fact that [https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/usr.html the /usr hierarchy] does contain a list of subdirectories pretty much identical [https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/the-root-directory.html to those of the root directory].
|-
! /
| '''dev/'''
| Nothing.
|random/> links to a random xkcd comic.
urandom/> links to [[221: Random Number]]
|}

In an additional fool it introduces the [https://uni.xkcd.com/ Unix XKCD] as a reference to the [https://en.wikipedia.org/wiki/Telenet Telenet]. (More on UniXKCD commands can be found [[721:_Flatland#UniXKCD|here]].)

==Transcript==
:[Empty frame with Cueball slightly right of center.]

:[Caption below the frame:]
:Editor's Note: Today's comic is optimized for local viewing. To see the full version, just save a copy of the image!

{{comic discussion}}



[[Category:Interactive comics]]
[[Category:April fools' comics]]

1975: Right Click

2018-04-02T16:40:49Z

Cvtsi2sd: Added explanation to the "infinite, identical subdirectories" inside /usr

{{comic
| number = 1975
| date = April 1, 2018
| title = Right Click
| image = right_click.png
| titletext = "Right-click or long press (where supported) to save!"
}}
'''NOTE: The above is the first panel of an interactive comic.''' 
To experience the interactive content, click [https://www.xkcd.com/1975/ here] or this link for [https://m.xkcd.com/1975/ mobile devices].

==Explanation==
{{incomplete|Please add an explanation table of all functions This is an April Fools comic, so it'll take a while to get organized and much longer to fill out. Do NOT delete this tag too soon.}}

This is an interactive comic which manipulates the context menu of the browser. This menu is typically accessible by a right-click or a long press on mobile devices without a mouse.

The comic uses {{w|Javascript}} and {{w|HTML5}} to override the standard context menu. Since modern browsers use the same features to integrate Add-ons into that menu the behave may be different depending on the browser environment.

The manipulated context menu is described below:
;Main Context Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! # !! Menu Item !! Explanation !! Sub-Menu Items
|-
!1
| '''Save'''
| Only appears after successfully completing the ADVENT.EXE game or getting the easter egg in mornington crescent.
| Save image> Downloads this image. [https://xkcd.com/1975/v6xso1_right_click_save.png]

|-
! 2
| '''File'''
| Normal submenu
|Close> Closes menu, does nothing.
Open: A:\, C:\, / (See more [[#Table - Filesystems Menu|below]])

Find: Where, When, How, (not usable) What, Why

|-
! 3
| '''Edit'''
| Enables a mode allowing the user to draw on the webpage. Pressing Esc asks "Aw, that looks nice though. Really delete?" and the page returns to normal if OK is clicked.
| None
|-
! 4
| '''System'''
| Normal submenu
|Shut Down> Changes the only menu option to "Power on", then once that is used, system returns to normal.

/ (See [[#Table - Filesystems Menu|below]])
|-
! 5
| '''View'''
| Normal submenu
|Cascade>Links to [http://wiki.xkcd.com/geohashing/Mt._St._Helens,_Washington]

Tile> Links to [[245: Floor Tiles]]

Minimize> Changes pointer to a smaller pointer.

Full Screen> Enters full screen.
|-
! 6
| '''Utilities'''
| Normal submenu
|Park drives> Nothing.

Check space usage> (cannot click) Space usage: -Dark matter -Hydrogen -Helium -Scattered clumps of heavier elements -Stars -Rocks -Some space probes -Earth

Spell check> English (links to [[1069: Alphabet]]) and Colors (links to [https://blog.xkcd.com/2010/05/03/color-survey-results/])

Train AI> links to [[1838: Machine Learning]]

Identify song> opens a long word-by-word menu for song lyrics; it's actually a menu-ized version of [[851: Na]].

Advanced> several Unix commands, all absurd (or dangerous) for some reason:
* <code>apt-get install /dev/null</code>: <code>apt-get</code> is the standard package manager used in Debian-derived Linux distributions (including Ubuntu); it is normally used to install software; <code>/dev/null</code> is the "bit-bucket" device on any Unix system, which can be used as a dummy output file to discard output or as a dummy empty input file. This command would attempt to install <code>/dev/null</code> (which is a device, not a package!) or, more correctly, would try to install a package reading its data from <code>/dev/null</code> (if <code>apt-get</code> is given a file name it tries to interpret it as a .deb package), which is obviously impossible.
* <code>brew install apt-get</code>: <code>brew</code> is a third-party package manager for macOS; it is generally used to install "missing" open-source utilities on a macOS system; the command is attempting to install the aforementioned <code>apt-get</code>, which is both impossible (<code>apt-get</code> doesn't run on macOS) and hilariously recursive (did you install a package manager - brew - to install another one?)
* <code>/usr/local/bin/wine xen-hypervisor.exe</code>: <code>wine</code> is a compatibility layer used to run Windows executables on Linux (and on macOS); the fact that it is in <code>/usr/local</code> hints that it has been manually compiled on this machine; Xen is a Linux-based hypervisor, i.e. a software used to run and manage virtual machines over a Linux host, but the .exe suffix here hints that it is a Windows executable. The command would try to launch a Windows build of a Linux-based virtual machine manager on a Unix machine through a Windows emulation layer (wine).
* <code>source .bash_history</code>: the <code>source</code> shell command reads the file that is given as argument and executes each of its rows as a command in the current shell, roughly as if you typed them in; <code>.bash_history</code> (located in the user home directory) is the file where the bash shell saves the history of the commands that have been run. This command would re-run all the command that have been typed in the shell.
* <code>rm -rf $DIRECTROY/*</code>: <code>rm -rf</code> deletes recursively and forcefully the paths it is given as arguments; <code>$DIRECTROY</code> is a shell variable, probably containing some directory that whoever typed in this command wanted to clean; however, it is misspelled (it says <code>$DIRECTROY</code>, not <code>$DIRECTORY</code>), and, due to how POSIX shell work, it is thus expanded to an empty string; so, the command becomes <code>rm -rf /*</code>, which deletes all the files and directories in the root of the disk, effectively killing the system instead of just deleting the content of some directory. Notice that this particular misspell manages to circumvent the builtin protection of many <code>rm</code> versions, which refuse to do a plain <code>rm -rf /</code>, as <code>/*</code> gets expanded by the shell, so <code>rm</code> never has the chance to see explicitly that you are killing all the data in the root directory.
* <code>:(){:|:&};:</code>: this is [https://askubuntu.com/q/159491/208527 a classic shell fork bomb], i.e. a small program that keeps launching copies of itself, until all resources have been exhausted or the user somehow manages to kill all its copies.
* <code>echo "source .bashrc" >> .bashrc</code>: <code>.bashrc</code> is a file that gets executed whenever the <code>bash</code> shell is started in interactive mode; this command appends the string <code>source .bashrc</code> to it, which effectively executes it again recursively; this would pretty much make it impossible to open an interactive shell when launching it with the default parameters.
* <code>alias gcc=php</code>: the <code>alias</code> shell builtin create an alias for another command; <code>gcc</code> is the GNU C compiler driver, which is used to compile programs written in the C language; <code>php</code> is the command-line interpreter for the PHP language. This line creates an alias such that when typing <code>gcc</code>, <code>php</code> is actually invoked, which would generate completely absurd error messages. This is doubly devious, as PHP isn't generally held in high esteem by large part of the programming community (especially by someone writing stuff in C).

'); DROP TABLE Menus;-- links to [[327: Exploits of a Mom]]
|-
! 7
| '''Games'''
| Normal submenu
| Twenty Questions> A Twenty Questions interface that gets really confusing.

Rock Paper Scissors> A Rock Paper Scissors game where the computer always matches your move.

D&D> A complex Dungeons and Dragons interface. Allows you to cast various spells from D&D 5e which link to various pages, including xkcd comics (e.g. [[1331: Frequency]]), what-ifs (e.g. {{what if|144|Saliva Pool}}) and other external sites (e.g. [https://www.nasa.gov/sun The Sun | NASA]).

ADVENT.EXE> A text-based game. If played correctly, you can win, unlocking 'Save'>'Save image' from the beginning menu, which links to [https://xkcd.com/1975/v6xso1_right_click_save.png]. 'ADVENT.EXE>Castle>Well>Wish for...' has links to comics [[572: Together]], [[1053: Ten Thousand]], [[152: Hamster Ball]], [[1196: Subways]], [[231: Cat Proximity]] and to what-if articles {{what if|111|All the Money}} and {{what if|9|Soul Mates}}.

Hoverboard> Links to [[1608: Hoverboard]].

Mornington Crescent> This is a simulation of the well-known game [https://en.wikipedia.org/wiki/Mornington_Crescent_(game) Mornington Crescent], which bears a surprising resemblance to London's [https://en.wikipedia.org/wiki/London_Underground Underground] railway network. Players name a station in turn, endeavouring to reach Mornington Crescent. The rules of play are very complicted and beyond the scope of this article; interested persons are referred to ''N. F. Stovold’s Mornington Crescent: Rules and Origins'' (sadly out of print). In this variation, one may reach 'Vauxhaull'>'Easter basket'>'Take egg', also allowing you to save.
|-
! 8
| '''Help'''
| Contains various submenus, all of which, barring Credits, loop back recursively to this menu:
|Tutorial
Support

Manual

Troubleshooting

FAQ

Guide

Q&A

User forums

--------------

Credits> 'Some people who helped with this comic:
[http://chromakode.com/ @chromakode]
[https://twitter.com/aiiane Amber]
[https://twitter.com/fadinginterest @fadinginterest]
[https://twitter.com/wirehead2501 Kat]
[https://twitter.com/cotrone Kevin]
[http://90d.ca/ Stereo]'
|-
! 9
| '''Do Crimes'''
| Contains several "crimes" that can be committed. This option is unlocked by File > Open > C:\ (or /home/user) > Bookmarks/ > Secret > Enable Dark Web.
| Steal Bitcoins > Grayed out.
Say swears > Several clean swears that all link to [[771: Period Speech]].

Hack > Three sub-options that link to various related comics. (Gibson: Nothing. Election: [[1019: First Post]]. Planet: [[1337: Hack]].)

Forge a Scrabble Tile > Several sub-options that don't do anything. (U, Z, <this menu option intentionally left blank>, and two special characters, one appearing like a reversed 'E' modeled on a 'C', or Russian 'Э', as low-pitched [eh], and the second being crossed swords)
|}

;Filesystems Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! Drive !! Menu Item !! Explanation !! Sub-Menu Items
|-
! A:\
| '''Insert'''
| Only appears before inserting a floppy disk.
|Floppy disk> Unlocks other options for drive A:\, which are identical to drive C:\
Chip card> A long sequence of being told 'Please wait. Authorizing...' ending in 'Chip error! REMOVE CARD NOW!'
|-
! C:\
| '''Documents/'''
| Nothing.
| None.
|-
! C:\
| '''Music/'''
| Leads into a long string of prompts for song lyrics. 'Hey now / Hey now na now / Sing "This Corrosion" to me' inverts the webpage's color.
|-
! C:\
| '''Bookmarks/'''
| Similar to Music/, Bookmarks/> Comics leads to a chain from which many comics are titled and linked. Bookmarks/> Secret> Enable Dark Web adds the 'Dark Web' option to the initial menu.
|-
! C:\
| '''Games/'''
| Same as 'Games' from the initial menu.
|-
! C:\
| '''Sequences/'''
| The options are the lines from a ''Tim and Eric'' sketch [http://knowyourmeme.com/memes/celery-man Celery Man]; the final option links to a YouTube video of the sketch.
| After several single-option menus, it links to this Youtube video. https://www.youtube.com/watch?v=MHWBEK8w_YY
|-
! /
| '''home/'''
| Nothing.
| guest> links to [//uni.xkcd.com]

user> Same files as C:\

root> Displays 'You are not in the sudoers file. This incident will be reported.'
|-
! /
| '''opt/'''
| Does nothing.
| None.
|-
! /
| '''sbin/'''
| Does nothing.
| None.
|-
! /
| '''usr/'''
| Opens an infinite sequence of options, each similar to the last, but replacing the previous selection with another folder; probably a reference to the fact that [https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/usr.html the /usr hierarchy] does contain a list of subdirectories pretty much identical [https://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/the-root-directory.html to those of the root directory].
|-
! /
| '''dev/'''
| Nothing.
|random/> links to a random xkcd comic.
urandom/> links to [[221: Random Number]]
|}

In an additional fool it introduces the [https://uni.xkcd.com/ Unix XKCD] as a reference to the [https://en.wikipedia.org/wiki/Telenet Telenet]. (More on UniXKCD commands can be found [[721:_Flatland#UniXKCD|here]].)

==Transcript==
:[Empty frame with Cueball slightly right of center.]

:[Caption below the frame:]
:Editor's Note: Today's comic is optimized for local viewing. To see the full version, just save a copy of the image!

{{comic discussion}}



[[Category:Interactive comics]]
[[Category:April fools' comics]]

1975: Right Click

2018-04-02T15:28:54Z

Cvtsi2sd: Added reference to 851: Na for Identify song

{{comic
| number = 1975
| date = April 1, 2018
| title = Right Click
| image = right_click.png
| titletext = "Right-click or long press (where supported) to save!"
}}
'''NOTE: The above is the first panel of an interactive comic.''' 
To experience the interactive content, click [https://www.xkcd.com/1975/ here] or this link for [https://m.xkcd.com/1975/ mobile devices].

==Explanation==
{{incomplete|Please add an explanation table of all functions This is an April Fools comic, so it'll take a while to get organized and much longer to fill out. Do NOT delete this tag too soon.}}

This is an interactive comic which manipulates the context menu of the browser. This menu is typically accessible by a right-click or a long press on mobile devices without a mouse.

The comic uses {{w|Javascript}} and {{w|HTML5}} to override the standard context menu. Since modern browsers use the same features to integrate Add-ons into that menu the behave may be different depending on the browser environment.

The manipulated context menu is described below:
;Main Context Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! # !! Menu Item !! Explanation !! Sub-Menu Items
|-
!1
| '''Save'''
| Only appears after successfully completing the ADVENT.EXE game.
| Save image> Downloads this image. [https://xkcd.com/1975/v6xso1_right_click_save.png]

|-
! 2
| '''File'''
| Normal submenu
|Close> Closes menu, does nothing.
Open: A:\, C:\, / (See more [[#Table - Filesystems Menu|below]])

Find: Where, When, How, (not usable) What, Why

|-
! 3
| '''Edit'''
| Enables a mode allowing the user to draw on the webpage. Pressing Esc asks "Aw, that looks nice though. Really delete?" and the page returns to normal if OK is clicked.
| None
|-
! 4
| '''System'''
| Normal submenu
|Shut Down> Changes the only menu option to "Power on", then once that is used, system returns to normal.

/ (See [[#Table - Filesystems Menu|below]])
|-
! 5
| '''View'''
| Normal submenu
|Cascade>Links to [http://wiki.xkcd.com/geohashing/Mt._St._Helens,_Washington]

Tile> Links to [[245: Floor Tiles]]

Minimize> Changes pointer to a smaller pointer.

Full Screen> Enters full screen.
|-
! 6
| '''Utilities'''
| Normal submenu
|Park drives> Nothing.

Check space usage> (cannot click) Space usage: -Dark matter -Hydrogen -Helium -Scattered clumps of heavier elements -Stars -Rocks -Some space probes -Earth

Spell check> English (links to [[1069: Alphabet]]) and Colors (links to [https://blog.xkcd.com/2010/05/03/color-survey-results/])

Train AI> links to [[1838: Machine Learning]]

Identify song> opens a long word-by-word menu for song lyrics; it's actually a menu-ized version of [[851: Na]].

Advanced> several Unix commands, all absurd (or dangerous) for some reason:
* <code>apt-get install /dev/null</code>: <code>apt-get</code> is the standard package manager used in Debian-derived Linux distributions (including Ubuntu); it is normally used to install software; <code>/dev/null</code> is the "bit-bucket" device on any Unix system, which can be used as a dummy output file to discard output or as a dummy empty input file. This command would attempt to install <code>/dev/null</code> (which is a device, not a package!) or, more correctly, would try to install a package reading its data from <code>/dev/null</code> (if <code>apt-get</code> is given a file name it tries to interpret it as a .deb package), which is obviously impossible.
* <code>brew install apt-get</code>: <code>brew</code> is a third-party package manager for macOS; it is generally used to install "missing" open-source utilities on a macOS system; the command is attempting to install the aforementioned <code>apt-get</code>, which is both impossible (<code>apt-get</code> doesn't run on macOS) and hilariously recursive (did you install a package manager - brew - to install another one?)
* <code>/usr/local/bin/wine xen-hypervisor.exe</code>: <code>wine</code> is a compatibility layer used to run Windows executables on Linux (and on macOS); the fact that it is in <code>/usr/local</code> hints that it has been manually compiled on this machine; Xen is a Linux-based hypervisor, i.e. a software used to run and manage virtual machines over a Linux host, but the .exe suffix here hints that it is a Windows executable. The command would try to launch a Windows build of a Linux-based virtual machine manager on a Unix machine through a Windows emulation layer (wine).
* <code>source .bash_history</code>: the <code>source</code> shell command reads the file that is given as argument and executes each of its rows as a command in the current shell, roughly as if you typed them in; <code>.bash_history</code> (located in the user home directory) is the file where the bash shell saves the history of the commands that have been run. This command would re-run all the command that have been typed in the shell.
* <code>rm -rf $DIRECTROY/*</code>: <code>rm -rf</code> deletes recursively and forcefully the paths it is given as arguments; <code>$DIRECTROY</code> is a shell variable, probably containing some directory that whoever typed in this command wanted to clean; however, it is misspelled (it says <code>$DIRECTROY</code>, not <code>$DIRECTORY</code>), and, due to how POSIX shell work, it is thus expanded to an empty string; so, the command becomes <code>rm -rf /*</code>, which deletes all the files and directories in the root of the disk, effectively killing the system instead of just deleting the content of some directory. Notice that this particular misspell manages to circumvent the builtin protection of many <code>rm</code> versions, which refuse to do a plain <code>rm -rf /</code>, as <code>/*</code> gets expanded by the shell, so <code>rm</code> never has the chance to see explicitly that you are killing all the data in the root directory.
* <code>:(){:|:&};:</code>: this is [https://askubuntu.com/q/159491/208527 a classic shell fork bomb], i.e. a small program that keeps launching copies of itself, until all resources have been exhausted or the user somehow manages to kill all its copies.
* <code>echo "source .bashrc" >> .bashrc</code>: <code>.bashrc</code> is a file that gets executed whenever the <code>bash</code> shell is started in interactive mode; this command appends the string <code>source .bashrc</code> to it, which effectively executes it again recursively; this would pretty much make it impossible to open an interactive shell when launching it with the default parameters.
* <code>alias gcc=php</code>: the <code>alias</code> shell builtin create an alias for another command; <code>gcc</code> is the GNU C compiler driver, which is used to compile programs written in the C language; <code>php</code> is the command-line interpreter for the PHP language. This line creates an alias such that when typing <code>gcc</code>, <code>php</code> is actually invoked, which would generate completely absurd error messages. This is doubly devious, as PHP isn't generally held in high esteem by large part of the programming community (especially by someone writing stuff in C).

'); DROP TABLE Menus;-- links to [[327: Exploits of a Mom]]
|-
! 7
| '''Games'''
| Normal submenu
| Twenty Questions> A Twenty Questions interface that gets really confusing.

Rock Paper Scissors> A Rock Paper Scissors game where the computer always matches your move.

D&D> A complex Dungeons and Dragons interface. Allows you to cast various spells from D&D 5e which link to various pages, including xkcd comics (e.g. [[1331: Frequency]]), what-ifs (e.g. {{what if|144|Saliva Pool}}) and other external sites (e.g. [https://www.nasa.gov/sun The Sun | NASA]).

ADVENT.EXE> A text-based game. If played correctly, you can win, unlocking 'Save'>'Save image' from the beginning menu, which links to [https://xkcd.com/1975/v6xso1_right_click_save.png]. 'ADVENT.EXE>Castle>Well>Wish for...' has links to comics [[572: Together]], [[1053: Ten Thousand]], [[152: Hamster Ball]], [[1196: Subways]], [[231: Cat Proximity]] and to what-if articles {{what if|111|All the Money}} and {{what if|9|Soul Mates}}.

Hoverboard> Links to [[1608: Hoverboard]].

Mornington Crescent> This is a simulation of the well-known game [https://en.wikipedia.org/wiki/Mornington_Crescent_(game) Mornington Crescent], which bears a surprising resemblance to London's [https://en.wikipedia.org/wiki/London_Underground Underground] railway network. Players name a station in turn, endeavouring to reach Mornington Crescent. The rules of play are very complicted and beyond the scope of this article; interested persons are referred to ''N. F. Stovold’s Mornington Crescent: Rules and Origins'' (sadly out of print). In this variation, one may reach 'Vauxhaull'>'Easter basket'>'Take egg', also allowing you to save.
|-
! 8
| '''Help'''
| Contains various submenus, all of which, barring Credits, loop back recursively to this menu:
|Tutorial
Support

Manual

Troubleshooting

FAQ

Guide

Q&A

User forums

--------------

Credits> 'Some people who helped with this comic:
[http://chromakode.com/ @chromakode]
[https://twitter.com/aiiane Amber]
[https://twitter.com/fadinginterest @fadinginterest]
[https://twitter.com/wirehead2501 Kat]
[https://twitter.com/cotrone Kevin]
[http://90d.ca/ Stereo]'
|-
! 9
| '''Do Crimes'''
| Contains several "crimes" that can be committed. This option is unlocked by File > Open > C:\ (or /home/user) > Bookmarks/ > Secret > Enable Dark Web.
| Steal Bitcoins > Grayed out.
Say swears > Several clean swears that all link to [[771: Period Speech]].

Hack > Three sub-options that link to various related comics. (Gibson: Nothing. Election: [[1019: First Post]]. Planet: [[1337: Hack]].)

Forge a Scrabble Tile > Several sub-options that don't do anything. (U, Z, <this menu option intentionally left blank>, and two special characters, one appearing like a reversed 'E' modeled on a 'C', or Russian 'Э', as low-pitched [eh], and the second being crossed swords)
|}

;Filesystems Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! Drive !! Menu Item !! Explanation !! Sub-Menu Items
|-
! A:\
| '''Insert'''
| Only appears before inserting a floppy disk.
|Floppy disk> Unlocks other options for drive A:\, which are identical to drive C:\
Chip card> A long sequence of being told 'Please wait. Authorizing...' ending in 'Chip error! REMOVE CARD NOW!'
|-
! C:\
| '''Documents/'''
| Nothing.
| None.
|-
! C:\
| '''Music/'''
| Leads into a long string of prompts for song lyrics. 'Hey now / Hey now na now / Sing "This Corrosion" to me' inverts the webpage's color.
|-
! C:\
| '''Bookmarks/'''
| Similar to Music/, Bookmarks/> Comics leads to a chain from which many comics are titled and linked. Bookmarks/> Secret> Enable Dark Web adds the 'Dark Web' option to the initial menu.
|-
! C:\
| '''Games/'''
| Same as 'Games' from the initial menu.
|-
! C:\
| '''Sequences/'''
| The options are the lines from a ''Tim and Eric'' sketch [http://knowyourmeme.com/memes/celery-man Celery Man]; the final option links to a YouTube video of the sketch.
| After several single-option menus, it links to this Youtube video. https://www.youtube.com/watch?v=MHWBEK8w_YY
|-
! /
| '''home/'''
| Nothing.
| guest> links to [//uni.xkcd.com]

user> Same files as C:\

root> Displays 'You are not in the sudoers file. This incident will be reported.'
|-
! /
| '''opt/'''
| Does nothing.
| None.
|-
! /
| '''sbin/'''
| Does nothing.
| None.
|-
! /
| '''usr/'''
| Opens an infinite sequence of options, each similar to the last, but replacing the previous selection with another folder.
|-
! /
| '''dev/'''
| Nothing.
|random/> links to a random xkcd comic.
urandom/> links to [[221: Random Number]]
|}

In an additional fool it introduces the [https://uni.xkcd.com/ Unix XKCD] as a reference to the [https://en.wikipedia.org/wiki/Telenet Telenet]. (More on UniXKCD commands can be found [[721:_Flatland#UniXKCD|here]].)

==Transcript==
:[Empty frame with Cueball slightly right of center.]

:[Caption below the frame:]
:Editor's Note: Today's comic is optimized for local viewing. To see the full version, just save a copy of the image!

{{comic discussion}}



[[Category:Interactive comics]]
[[Category:April fools' comics]]

1975: Right Click

2018-04-02T15:19:55Z

Cvtsi2sd: Added explanation of the Unix commands in the Utilities>Advanced submenu

{{comic
| number = 1975
| date = April 1, 2018
| title = Right Click
| image = right_click.png
| titletext = "Right-click or long press (where supported) to save!"
}}
'''NOTE: The above is the first panel of an interactive comic.''' 
To experience the interactive content, click [https://www.xkcd.com/1975/ here] or this link for [https://m.xkcd.com/1975/ mobile devices].

==Explanation==
{{incomplete|Please add an explanation table of all functions This is an April Fools comic, so it'll take a while to get organized and much longer to fill out. Do NOT delete this tag too soon.}}

This is an interactive comic which manipulates the context menu of the browser. This menu is typically accessible by a right-click or a long press on mobile devices without a mouse.

The comic uses {{w|Javascript}} and {{w|HTML5}} to override the standard context menu. Since modern browsers use the same features to integrate Add-ons into that menu the behave may be different depending on the browser environment.

The manipulated context menu is described below:
;Main Context Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! # !! Menu Item !! Explanation !! Sub-Menu Items
|-
!1
| '''Save'''
| Only appears after successfully completing the ADVENT.EXE game.
| Save image> Downloads this image. [https://xkcd.com/1975/v6xso1_right_click_save.png]

|-
! 2
| '''File'''
| Normal submenu
|Close> Closes menu, does nothing.
Open: A:\, C:\, / (See more [[#Table - Filesystems Menu|below]])

Find: Where, When, How, (not usable) What, Why

|-
! 3
| '''Edit'''
| Enables a mode allowing the user to draw on the webpage. Pressing Esc asks "Aw, that looks nice though. Really delete?" and the page returns to normal if OK is clicked.
| None
|-
! 4
| '''System'''
| Normal submenu
|Shut Down> Changes the only menu option to "Power on", then once that is used, system returns to normal.

/ (See [[#Table - Filesystems Menu|below]])
|-
! 5
| '''View'''
| Normal submenu
|Cascade>Links to [http://wiki.xkcd.com/geohashing/Mt._St._Helens,_Washington]

Tile> Links to [[245: Floor Tiles]]

Minimize> Changes pointer to a smaller pointer.

Full Screen> Enters full screen.
|-
! 6
| '''Utilities'''
| Normal submenu
|Park drives> Nothing.

Check space usage> (cannot click) Space usage: -Dark matter -Hydrogen -Helium -Scattered clumps of heavier elements -Stars -Rocks -Some space probes -Earth

Spell check> English (links to [[1069: Alphabet]]) and Colors (links to [https://blog.xkcd.com/2010/05/03/color-survey-results/])

Train AI> links to [[1838: Machine Learning]]

Identify song> opens a long word-by-word menu for song lyrics.

Advanced> several Unix commands, all absurd (or dangerous) for some reason:
* <code>apt-get install /dev/null</code>: <code>apt-get</code> is the standard package manager used in Debian-derived Linux distributions (including Ubuntu); it is normally used to install software; <code>/dev/null</code> is the "bit-bucket" device on any Unix system, which can be used as a dummy output file to discard output or as a dummy empty input file. This command would attempt to install <code>/dev/null</code> (which is a device, not a package!) or, more correctly, would try to install a package reading its data from <code>/dev/null</code> (if <code>apt-get</code> is given a file name it tries to interpret it as a .deb package), which is obviously impossible.
* <code>brew install apt-get</code>: <code>brew</code> is a third-party package manager for macOS; it is generally used to install "missing" open-source utilities on a macOS system; the command is attempting to install the aforementioned <code>apt-get</code>, which is both impossible (<code>apt-get</code> doesn't run on macOS) and hilariously recursive (did you install a package manager - brew - to install another one?)
* <code>/usr/local/bin/wine xen-hypervisor.exe</code>: <code>wine</code> is a compatibility layer used to run Windows executables on Linux (and on macOS); the fact that it is in <code>/usr/local</code> hints that it has been manually compiled on this machine; Xen is a Linux-based hypervisor, i.e. a software used to run and manage virtual machines over a Linux host, but the .exe suffix here hints that it is a Windows executable. The command would try to launch a Windows build of a Linux-based virtual machine manager on a Unix machine through a Windows emulation layer (wine).
* <code>source .bash_history</code>: the <code>source</code> shell command reads the file that is given as argument and executes each of its rows as a command in the current shell, roughly as if you typed them in; <code>.bash_history</code> (located in the user home directory) is the file where the bash shell saves the history of the commands that have been run. This command would re-run all the command that have been typed in the shell.
* <code>rm -rf $DIRECTROY/*</code>: <code>rm -rf</code> deletes recursively and forcefully the paths it is given as arguments; <code>$DIRECTROY</code> is a shell variable, probably containing some directory that whoever typed in this command wanted to clean; however, it is misspelled (it says <code>$DIRECTROY</code>, not <code>$DIRECTORY</code>), and, due to how POSIX shell work, it is thus expanded to an empty string; so, the command becomes <code>rm -rf /*</code>, which deletes all the files and directories in the root of the disk, effectively killing the system instead of just deleting the content of some directory. Notice that this particular misspell manages to circumvent the builtin protection of many <code>rm</code> versions, which refuse to do a plain <code>rm -rf /</code>, as <code>/*</code> gets expanded by the shell, so <code>rm</code> never has the chance to see explicitly that you are killing all the data in the root directory.
* <code>:(){:|:&};:</code>: this is [https://askubuntu.com/q/159491/208527 a classic shell fork bomb], i.e. a small program that keeps launching copies of itself, until all resources have been exhausted or the user somehow manages to kill all its copies.
* <code>echo "source .bashrc" >> .bashrc</code>: <code>.bashrc</code> is a file that gets executed whenever the <code>bash</code> shell is started in interactive mode; this command appends the string <code>source .bashrc</code> to it, which effectively executes it again recursively; this would pretty much make it impossible to open an interactive shell when launching it with the default parameters.
* <code>alias gcc=php</code>: the <code>alias</code> shell builtin create an alias for another command; <code>gcc</code> is the GNU C compiler driver, which is used to compile programs written in the C language; <code>php</code> is the command-line interpreter for the PHP language. This line creates an alias such that when typing <code>gcc</code>, <code>php</code> is actually invoked, which would generate completely absurd error messages. This is doubly devious, as PHP isn't generally held in high esteem by large part of the programming community (especially by someone writing stuff in C).

'); DROP TABLE Menus;-- links to [[327: Exploits of a Mom]]
|-
! 7
| '''Games'''
| Normal submenu
| Twenty Questions> A Twenty Questions interface that gets really confusing.

Rock Paper Scissors> A Rock Paper Scissors game where the computer always matches your move.

D&D> A complex Dungeons and Dragons interface. Allows you to cast various spells from D&D 5e which link to various pages, including xkcd comics (e.g. [[1331: Frequency]]), what-ifs (e.g. {{what if|144|Saliva Pool}}) and other external sites (e.g. [https://www.nasa.gov/sun The Sun | NASA]).

ADVENT.EXE> A text-based game. If played correctly, you can win, unlocking 'Save'>'Save image' from the beginning menu, which links to [https://xkcd.com/1975/v6xso1_right_click_save.png]. 'ADVENT.EXE>Castle>Well>Wish for...' has links to comics [[572: Together]], [[1053: Ten Thousand]], [[152: Hamster Ball]], [[1196: Subways]], [[231: Cat Proximity]] and to what-if articles {{what if|111|All the Money}} and {{what if|9|Soul Mates}}.

Hoverboard> Links to [[1608: Hoverboard]].

Mornington Crescent> This is a simulation of the well-known game [https://en.wikipedia.org/wiki/Mornington_Crescent_(game) Mornington Crescent], which bears a surprising resemblance to London's [https://en.wikipedia.org/wiki/London_Underground Underground] railway network. Players name a station in turn, endeavouring to reach Mornington Crescent. The rules of play are very complicted and beyond the scope of this article; interested persons are referred to ''N. F. Stovold’s Mornington Crescent: Rules and Origins'' (sadly out of print). In this variation, one may reach 'Vauxhaull'>'Easter basket'>'Take egg', also allowing you to save.
|-
! 8
| '''Help'''
| Contains various submenus, all of which, barring Credits, loop back recursively to this menu:
|Tutorial
Support

Manual

Troubleshooting

FAQ

Guide

Q&A

User forums

--------------

Credits> 'Some people who helped with this comic:
[http://chromakode.com/ @chromakode]
[https://twitter.com/aiiane Amber]
[https://twitter.com/fadinginterest @fadinginterest]
[https://twitter.com/wirehead2501 Kat]
[https://twitter.com/cotrone Kevin]
[http://90d.ca/ Stereo]'
|-
! 9
| '''Do Crimes'''
| Contains several "crimes" that can be committed. This option is unlocked by File > Open > C:\ (or /home/user) > Bookmarks/ > Secret > Enable Dark Web.
| Steal Bitcoins > Grayed out.
Say swears > Several clean swears that all link to [[771: Period Speech]].

Hack > Three sub-options that link to various related comics. (Gibson: Nothing. Election: [[1019: First Post]]. Planet: [[1337: Hack]].)

Forge a Scrabble Tile > Several sub-options that don't do anything. (U, Z, <this menu option intentionally left blank>, and two special characters, one appearing like a reversed 'E' modeled on a 'C', or Russian 'Э', as low-pitched [eh], and the second being crossed swords)
|}

;Filesystems Menu

{| border =1 width=100% cellpadding=5 class="wikitable"
! Drive !! Menu Item !! Explanation !! Sub-Menu Items
|-
! A:\
| '''Insert'''
| Only appears before inserting a floppy disk.
|Floppy disk> Unlocks other options for drive A:\, which are identical to drive C:\
Chip card> A long sequence of being told 'Please wait. Authorizing...' ending in 'Chip error! REMOVE CARD NOW!'
|-
! C:\
| '''Documents/'''
| Nothing.
| None.
|-
! C:\
| '''Music/'''
| Leads into a long string of prompts for song lyrics. 'Hey now / Hey now na now / Sing "This Corrosion" to me' inverts the webpage's color.
|-
! C:\
| '''Bookmarks/'''
| Similar to Music/, Bookmarks/> Comics leads to a chain from which many comics are titled and linked. Bookmarks/> Secret> Enable Dark Web adds the 'Dark Web' option to the initial menu.
|-
! C:\
| '''Games/'''
| Same as 'Games' from the initial menu.
|-
! C:\
| '''Sequences/'''
| Fill in, I have no clue.
| After several single-option menus, it links to this Youtube video. https://www.youtube.com/watch?v=MHWBEK8w_YY
|-
! /
| '''home/'''
| Nothing.
| guest> links to [//uni.xkcd.com]

user> Same files as C:\

root> Displays 'You are not in the sudoers file. This incident will be reported.'
|-
! /
| '''opt/'''
| Does nothing.
| None.
|-
! /
| '''sbin/'''
| Does nothing.
| None.
|-
! /
| '''usr/'''
| Opens an infinite sequence of options, each similar to the last, but replacing the previous selection with another folder.
|-
! /
| '''dev/'''
| Nothing.
|random/> links to a random xkcd comic.
urandom/> links to [[221: Random Number]]
|}

In an additional fool it introduces the [https://uni.xkcd.com/ Unix XKCD] as a reference to the [https://en.wikipedia.org/wiki/Telenet Telenet]. (More on UniXKCD commands can be found [[721:_Flatland#UniXKCD|here]].)

==Transcript==
:[Empty frame with Cueball slightly right of center.]

:[Caption below the frame:]
:Editor's Note: Today's comic is optimized for local viewing. To see the full version, just save a copy of the image!

{{comic discussion}}



[[Category:Interactive comics]]
[[Category:April fools' comics]]