2599: Spacecraft Debris Odds Ratio - Revision history

Chronotix: /* Explanation */

2026-03-16T20:40:39Z

‎Explanation

42.book.addict at 17:37, 3 December 2025

2025-12-03T17:37:46Z

FaviFake: yeah good call i guess. i made it more fluent (your style and mine aren't exactly similar, but this should make the paragraph less jarring for readers)

2025-03-02T21:17:27Z

yeah good call i guess. i made it more fluent (your style and mine aren't exactly similar, but this should make the paragraph less jarring for readers)

172.68.205.151: /* Trivia */ Hard to say whether the participle or the article is the intended 'ultimate' form, just that they don't work together.

2025-03-02T20:45:24Z

‎Trivia: Hard to say whether the participle or the article is the intended 'ultimate' form, just that they don't work together.

FaviFake: /* Trivia */

2025-03-02T10:56:08Z

‎Trivia

FaviFake: /* Trivia */

2025-03-02T10:55:45Z

‎Trivia

42.book.addict at 17:34, 1 November 2024

2024-11-01T17:34:16Z

172.69.22.210: /* Explanation */

2023-11-04T03:50:04Z

‎Explanation

172.69.22.211: /* Explanation */

2023-11-04T03:49:31Z

‎Explanation

172.69.22.211: /* Explanation */

2023-11-04T03:48:28Z

‎Explanation

@@ Line 30: / Line 30: @@
 The "280% increase" of the title text is also an error, though perhaps not for reasons you might assume at first glance (the correct calculation is not "300% − 30% = 270%"). To "increase by 300%" means to add 300% on top of the original 100% (=400%, so multiplied by 4), while to "decrease by 30%" means to remove 30% from the original 100% (=70%, so multiplied by 0.7). Combining these (which is very very wrong!) would mean multiplying by both, for an overall change of 4.0 × 0.7 = 2.8, or 280%. However, this should be read as an increase ''to'' 280% of its old value, not ''by'' 280% (you started at 100% and added 180%). But this is a very, very wrong way of doing the math because these are probabilities of very different things with very different scales (if you threw out 30% of your dishware but in that same period also acquired 3 toothpicks on top of your original 1 toothpick, would you say that your kitchen stuff increased by 180%?). The correct way of combining the two probabilities would be to translate them onto the same scale - the overall chance of death - which would be done by multiplying each value with its probability of happening at all. For example, if the chance of dying from cardiovascular disease was 50% and the chance of being killed by a bear was 0.1%, the overall chance of dying from either would be the sum, 50.1%. Both probabilities are affected by going outside; the new chances are now 50%*0.7=35% and 0.1%*4=0.4% and the combined chance of dying from either is now 35.4% - a significant DEcrease from the original 50.1%.
-The specific reference to falling spacecraft is likely inspired by events happening around the time of this comics release (March 2022).  Around a month before this was posted, the head of the Russian space agency, {{w|Roscosmos}}, warned that sanctions against Russia (mostly those over the {{w|2022 Russian invasion of Ukraine}}) could result in the {{w|International Space Station}} crashing.  Since the Russian section of the space station is the one that provides propulsion (although it is built to rely on the power generated by the other sections), this was taken seriously and as of when this was posted, {{w|NASA}} was trying to come up with alternative stabilization strategies in case the situation worsened. There was also a recent [https://www-uol-com-br.translate.goog/tilt/noticias/redacao/2022/03/17/parte-do-foguete-spacex-e-encontrada-por-morador-do-pr.htm?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=pt-BR&_x_tr_pto=wapp report] of some 600 kg space rocket debris found in Brazil.
+The specific reference to falling spacecraft is likely inspired by events happening around the time of this comic's release (March 2022).  Around a month before this was posted, the head of the Russian space agency, {{w|Roscosmos}}, warned that sanctions against Russia (mostly those over the {{w|2022 Russian invasion of Ukraine}}) could result in the {{w|International Space Station}} crashing.  Since the Russian section of the space station is the one that provides propulsion (although it is built to rely on the power generated by the other sections), this was taken seriously and as of when this was posted, {{w|NASA}} was trying to come up with alternative stabilization strategies in case the situation worsened. There was also a recent [https://www-uol-com-br.translate.goog/tilt/noticias/redacao/2022/03/17/parte-do-foguete-spacex-e-encontrada-por-morador-do-pr.htm?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=pt-BR&_x_tr_pto=wapp report] of some 600 kg space rocket debris found in Brazil.
 ==Transcript==

@@ Line 57: / Line 57: @@
 ==Trivia==
-*In the [https://www.explainxkcd.com/wiki/images/archive/d/d5/20220329223238%21spacecraft_debris_odds_ratio.png original version of the comic], the Y-axis was labelled "Hours spent outdoors", but it was later changed to specify "Hours spent outdoors ''per day''", which makes more sense. However, when the updated image was uploaded, it had a much larger size than normal, because Randall used the same file for both the normal "double-sized" image and the "regular" size. This resulted in [https://web.archive.org/web/20220329014721/http://xkcd.com/ the comic breaking the boundaries of the website], before it was fixed. This had happened before with [[2576: Control Group]]: see that comic's [[2576: Control Group#Trivia|trivia section]].
+*In the [[:File:2599- Spacecraft Debris Odds Ratio Image scaling off.png|original version of the comic]], the Y-axis was labelled "Hours spent outdoors", but it was later changed to specify "Hours spent outdoors ''per day''", which makes more sense. However, when the updated image was uploaded, it had a much larger size than normal, because Randall used the same file for both the normal "double-sized" image and the "regular" size. This resulted in [https://web.archive.org/web/20220329014721/http://xkcd.com/ the comic breaking the boundaries of the website], before it was fixed. This had happened before with [[2576: Control Group]]: see that comic's [[2576: Control Group#Trivia|trivia section]].
 *This comic's title text has a typo: it says "That's a 280% increase'''d'''!". Randall's intention might have been to say "That's a 280% increase!" (without the "d") or "That's 280% increased!" (without the {{w|Article (grammar)#Indefinite article|indefinite article}} "a"). Either way, a fragment of the original intention was left in when the phrase's tense was updated with the other. This typo has never been fixed and is included in the current title text.

@@ Line 59: / Line 59: @@
 *In the [https://www.explainxkcd.com/wiki/images/archive/d/d5/20220329223238%21spacecraft_debris_odds_ratio.png original version of the comic], the Y-axis was labelled "Hours spent outdoors", but it was later changed to specify "Hours spent outdoors ''per day''", which makes more sense. However, when the updated image was uploaded, it had a much larger size than normal, because Randall used the same file for both the normal "double-sized" image and the "regular" size. This resulted in [https://web.archive.org/web/20220329014721/http://xkcd.com/ the comic breaking the boundaries of the website], before it was fixed. This had happened before with [[2576: Control Group]]: see that comic's [[2576: Control Group#Trivia|trivia section]].
-*This comic's title text has a typo. It says "That's a 280% increase'''d'''!" instead of "That's a 280% increase!". Alternatively, the intention was to say something like "That's 280% increased!", and it is the {{w|Article (grammar)#Indefinite article|indefinite article}} which was erroneously included. Or, either way, a fragment of the original intention was left in when the phrase's tense was updated with the other. This typo has never been fixed and is included in the current title text.
+*This comic's title text has a typo: it says "That's a 280% increase'''d'''!". Randall's intention might have been to say "That's a 280% increase!" (without the "d") or "That's 280% increased!" (without the {{w|Article (grammar)#Indefinite article|indefinite article}} "a"). Either way, a fragment of the original intention was left in when the phrase's tense was updated with the other. This typo has never been fixed and is included in the current title text.
 {{comic discussion}}

@@ Line 59: / Line 59: @@
 *In the [https://www.explainxkcd.com/wiki/images/archive/d/d5/20220329223238%21spacecraft_debris_odds_ratio.png original version of the comic], the Y-axis was labelled "Hours spent outdoors", but it was later changed to specify "Hours spent outdoors ''per day''", which makes more sense. However, when the updated image was uploaded, it had a much larger size than normal, because Randall used the same file for both the normal "double-sized" image and the "regular" size. This resulted in [https://web.archive.org/web/20220329014721/http://xkcd.com/ the comic breaking the boundaries of the website], before it was fixed. This had happened before with [[2576: Control Group]]: see that comic's [[2576: Control Group#Trivia|trivia section]].
-*This comic's title text has a typo. It says "That's a 280% increase'''d'''!" instead of "That's a 280% increase!". This typo has never been fixed and is included in the current title text.
+*This comic's title text has a typo. It says "That's a 280% increase'''d'''!" instead of "That's a 280% increase!". Alternatively, the intention was to say something like "That's 280% increased!", and it is the {{w|Article (grammar)#Indefinite article|indefinite article}} which was erroneously included. Or, either way, a fragment of the original intention was left in when the phrase's tense was updated with the other. This typo has never been fixed and is included in the current title text.
 {{comic discussion}}

@@ Line 59: / Line 59: @@
 *In the [https://www.explainxkcd.com/wiki/images/archive/d/d5/20220329223238%21spacecraft_debris_odds_ratio.png original version of the comic], the Y-axis was labelled "Hours spent outdoors", but it was later changed to specify "Hours spent outdoors ''per day''", which makes more sense. However, when the updated image was uploaded, it had a much larger size than normal, because Randall used the same file for both the normal "double-sized" image and the "regular" size. This resulted in [https://web.archive.org/web/20220329014721/http://xkcd.com/ the comic breaking the boundaries of the website], before it was fixed. This had happened before with [[2576: Control Group]]: see that comic's [[2576: Control Group#Trivia|trivia section]].
-*This comic's title text has a typo. It says "That's a 280% increased!" instead of "That's a 280% increase!". This typo has never been fixed and is included in the current title text.
+*This comic's title text has a typo. It says "That's a 280% increase'''d'''!" instead of "That's a 280% increase!". This typo has never been fixed and is included in the current title text.
 {{comic discussion}}

@@ Line 25: / Line 25: @@
 [[1429: Data|The data]] are shown on a [[1162: Log Scale|log scale]]. Logarithmic scales are used when you have both very small and very large values and want to depict their relative differences in a single plot without making the small values look like zero or cutting off the large values. The data shown here do not have huge differences - there is no good reason for using a log scale. However, the log scale is conveniently chosen to make the error bars look like they have the same length. They do not. The error bar for the last data point is actually twice as large as that for the first data point.
 The title text continues the misuse of statistics by insinuating that a 30% decrease of cardiovascular disease resulting from going outside (and exercising) is outweighed by a simultaneous 300% increase of risk of being killed by a bear. As shown in [[1102: Fastest-Growing]], the percentage increase/decrease alone of something has little meaning; the context of the original size is needed to evaluate how impressive the change really is. And in this case, the probability of dying from a cardiovascular disease is much, MUCH higher than the probability of being attacked and killed by a bear, so the moderate decrease of the former has much more impact on one's overall life expectancy than even a huge increase of the latter (unless you live in an area that has many bears, in which case your best bet is to take appropriate precautions rather than to never go outside at all).
 The "280% increase" of the title text is also an error, though perhaps not for reasons you might assume at first glance (the correct calculation is not "300% − 30% = 270%"). To "increase by 300%" means to add 300% on top of the original 100% (=400%, so multiplied by 4), while to "decrease by 30%" means to remove 30% from the original 100% (=70%, so multiplied by 0.7). Combining these (which is very very wrong!) would mean multiplying by both, for an overall change of 4.0 × 0.7 = 2.8, or 280%. However, this should be read as an increase ''to'' 280% of its old value, not ''by'' 280% (you started at 100% and added 180%). But this is a very, very wrong way of doing the math because these are probabilities of very different things with very different scales (if you threw out 30% of your dishware but in that same period also acquired 3 toothpicks on top of your original 1 toothpick, would you say that your kitchen stuff increased by 180%?). The correct way of combining the two probabilities would be to translate them onto the same scale - the overall chance of death - which would be done by multiplying each value with its probability of happening at all. For example, if the chance of dying from cardiovascular disease was 50% and the chance of being killed by a bear was 0.1%, the overall chance of dying from either would be the sum, 50.1%. Both probabilities are affected by going outside; the new chances are now 50%*0.7=35% and 0.1%*4=0.4% and the combined chance of dying from either is now 35.4% - a significant DEcrease from the original 50.1%.
 The specific reference to falling spacecraft is likely inspired by events happening around the time of this comics release (March 2022).  Around a month before this was posted, the head of the Russian space agency, {{w|Roscosmos}}, warned that sanctions against Russia (mostly those over the {{w|2022 Russian invasion of Ukraine}}) could result in the {{w|International Space Station}} crashing.  Since the Russian section of the space station is the one that provides propulsion (although it is built to rely on the power generated by the other sections), this was taken seriously and as of when this was posted, {{w|NASA}} was trying to come up with alternative stabilization strategies in case the situation worsened. There was also a recent [https://www-uol-com-br.translate.goog/tilt/noticias/redacao/2022/03/17/parte-do-foguete-spacex-e-encontrada-por-morador-do-pr.htm?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=pt-BR&_x_tr_pto=wapp report] of some 600 kg space rocket debris found in Brazil.

← Older revision		Revision as of 03:50, 4 November 2023
Line 24:		Line 24:
	The error bars (the lines extending from the points in the graph) are HUGE compared to the effect they measured. Error bars define the range in which the true value might be - here, for 2-4 hours the true value could be an increase by 2, or a small DEcrease of the probability.		The error bars (the lines extending from the points in the graph) are HUGE compared to the effect they measured. Error bars define the range in which the true value might be - here, for 2-4 hours the true value could be an increase by 2, or a small DEcrease of the probability.

−	[[1429: Data\|The data]] are shown on a [[1162: Log Scale]]. Logarithmic scales are used when you have both very small and very large values and want to depict their relative differences in a single plot without making the small values look like zero or cutting off the large values. The data shown here do not have huge differences - there is no good reason for using a log scale. However, the log scale is conveniently chosen to make the error bars look like they have the same length. They do not. The error bar for the last data point is actually twice as large as that for the first data point.	+	[[1429: Data\|The data]] are shown on a [[1162: Log Scale\|log scale]]. Logarithmic scales are used when you have both very small and very large values and want to depict their relative differences in a single plot without making the small values look like zero or cutting off the large values. The data shown here do not have huge differences - there is no good reason for using a log scale. However, the log scale is conveniently chosen to make the error bars look like they have the same length. They do not. The error bar for the last data point is actually twice as large as that for the first data point.

← Older revision		Revision as of 03:49, 4 November 2023
Line 24:		Line 24:
	The error bars (the lines extending from the points in the graph) are HUGE compared to the effect they measured. Error bars define the range in which the true value might be - here, for 2-4 hours the true value could be an increase by 2, or a small DEcrease of the probability.		The error bars (the lines extending from the points in the graph) are HUGE compared to the effect they measured. Error bars define the range in which the true value might be - here, for 2-4 hours the true value could be an increase by 2, or a small DEcrease of the probability.

−	The data are shown on a [[1162: Log Scale]]. Logarithmic scales are used when you have both very small and very large values and want to depict their relative differences in a single plot without making the small values look like zero or cutting off the large values. The data shown here do not have huge differences - there is no good reason for using a log scale. However, the log scale is conveniently chosen to make the error bars look like they have the same length. They do not. The error bar for the last data point is actually twice as large as that for the first data point.	+	[[1429: Data\|The data]] are shown on a [[1162: Log Scale]]. Logarithmic scales are used when you have both very small and very large values and want to depict their relative differences in a single plot without making the small values look like zero or cutting off the large values. The data shown here do not have huge differences - there is no good reason for using a log scale. However, the log scale is conveniently chosen to make the error bars look like they have the same length. They do not. The error bar for the last data point is actually twice as large as that for the first data point.

@@ Line 17: / Line 17: @@
 The results are presented not as an overall probability but rather as an {{w|Odds_ratio|odds ratio}} of the probabilities. The odds ratio is defined as p(A happens in presence of B)/p(A happens in absence of B), which here would be p(space debris head injury after Xh spent outside and 24-Xh inside)/p(space debris head injury after 24h spent inside). The resulting value tells you how much more likely an outcome becomes if you do (or have) A. E.g. the bottom line of the graph in the comic means that spending 11+ hours outside will make it 3 times as likely to get a head injury from space debris compared to not being outside at all.
-However, while odds ratios can be useful they tend to hide the scale of a probability - e.g. 0.00000000002%/0.00000000001% = 2, the outcome became twice as likely but the probability only rose by 0.00000000001%. And since the odds of being hit in the head by (any part of) a falling spacecraft are [https://www.livescience.com/33511-falling-nasa-satellite-uars-risk.html astronomically ([[no pun intended]])low to begin with], even quadrupling it still results in a negligible probability.
+However, while odds ratios can be useful they tend to hide the scale of a probability - e.g. 0.00000000002%/0.00000000001% = 2, the outcome became twice as likely but the probability only rose by 0.00000000001%. And since the odds of being hit in the head by (any part of) a falling spacecraft are [https://www.livescience.com/33511-falling-nasa-satellite-uars-risk.html astronomically ([[559: No Pun Intended |no pun intended]]) low to begin with], even quadrupling it still results in a negligible probability.
 The choice of hour brackets instead of a linear time scale is suspicious. Monte Carlo simulations involve a huge number of computations; the scientists should have more than enough data to plot the odds ratio for every additional hour spent outside. Moreover, each hour bracket has a different size - why didn't they use a regular binning like e.g. 1-3, 4-6, 7-9, 10-12? One might suspect that they wanted to conceal inconsistencies and that the underlying data points by themselves don't look nearly as convincing.