explain xkcd - User contributions [en]

1282: Monty Hall

2013-10-25T14:47:46Z

213.86.4.78: /* Explanation */

{{comic
| number = 1282
| date = October 25, 2013
| title = Monty Hall
| image = monty hall.png
| titletext = A few minutes later, the goat from behind door C drives away in the car.
}}

==Explanation==
This comic is a reference to the {{w|Monty Hall Problem}}, a probability puzzle based on the US game show '{{w|Let's Make a Deal}}' and named after its original host, {{w|Monty Hall}}. The premise of the show was that Hall would offer "deals" to contestants pulled from the audience in which they could win cash and prizes. Some deals involved games/tasks the contestant had to perform, while others simply involved the contestant making choices between a series of doors or boxes. In such games of choice, there were often several prizes and typically at least one "zonk": The show's name for an undesirable "gag" prize, which on the original Monty Hall version of the show were frequently animals such as goats.

In the classic version of the Monty Problem, a contestant is offered a choice of three doors. Behind two doors is a goat, and behind one of them is a car. First, the contestant chooses a door, which remains closed. The host then opens one of the two remaining doors and reveals a goat. The contestant is then offered a final choice of whether to switch his pick to the remaining closed door, or keep the door they original chose. The problem involves an analysis of the the probability of the contestant choosing the car given certain circumstances.

The problem (as does the game show) assumes that a contestant would want to win a car, and would be disappointed to win a goat (a zonk), which most contestants would have no ability to house, and no use for. It appears that [[Beret Guy]], upon the host revealing that door B has a goat behind it, chooses to take the goat to keep as a pet, which makes them both very happy.

The title text references the car and the remaining goat, untouched behind the remaining doors.

===The Monty Hall Problem===
:''for an in-depth analysis of the Monty Hall Problem, see {{w|Monty Hall Problem|its article at Wikipedia}}''
The apparent "paradox" of the Monty Hall Problem is that many people's initial reaction once the host opens a door to reveal a goat, is that there are two remaining doors, one with a car and one with a goat; and therefore there is an equal probability the car is behing each door. many people therefore believe that switching makes no difference to the odds of winning a car.

However, assuming that the host has knowledge of which doors contain goats, and that his choice of which door to open is always an unchosen door containing a goat, it is actually twice as likely that the contestant will win the car if they switch than if they keep their original choice. This is because the contestant initially had a one-in-three chance of choosing the car (and a two-in-three chance of choosing a goat). Switching always wins the car in those two-thirds of cases where the contestant initially chose a goat. The probability of winning by switching is therefore the same as the probability that the contestant initially choose a goat.

The switch essentially gives the contestant ''both'' remaining doors instead of just the ''one'' door originally chosen. Because the host ''always'' has at least one "goat-door" available to open, the fact that the host reveals a goat does not provide the contestant any new information about their initially chosen door. The inital door still has a two-in-three chance of being a goat, and switching still has a two-in-three chance of winning. Opening a goat-door simply shifts all of the probability of the remaining two doors being a car to the remaining unchosen door.

There has been great debate about the precise wording of the problem, and what assumptions or rules might apply. Variants of the problem have the host open one of the two remaining doors at random, which could result in the car being revealed, and the game ending. In that scenario, if a goat is revealed, there is in fact an equal probability of winning by switching or keeping the initial door.

==Transcript==
:[A game show presenter is standing in front of three doors, the left door labeled "A", the right door labeled "C", and the middle door presumably labeled "B". The "B" door is open. Beret Guy is walking away with a goat.]
:Beret Guy: ...And my yard has so much grass, and I'll teach you tricks, and...

{{comic discussion}}
[[Category:Comics featuring Beret Guy]]

Talk:1277: Ayn Random

2013-10-21T15:09:50Z

213.86.4.78:

I think that should be /(\b[plurandy]+\b ?){2}/i.

[[Special:Contributions/173.66.108.213|173.66.108.213]] 05:12, 14 October 2013 (UTC)

I agree. I was confused for a while about what the b's were doing.

[[Special:Contributions/99.126.178.56|99.126.178.56]] 06:57, 14 October 2013 (UTC)

Maybe it's time to have an Ayn Rand category? --[[Special:Contributions/141.89.226.146|141.89.226.146]] 07:34, 14 October 2013 (UTC)

Can someone explain to the mathematically challenged *how* the list of names fits the regular expression? [[Special:Contributions/141.2.75.23|141.2.75.23]] 09:14, 14 October 2013 (UTC)
: Agreed, I would like to understand what the hell is going on with that. --[[User:Zagorath|Zagorath]] ([[User talk:Zagorath|talk]]) 09:20, 14 October 2013 (UTC)
: How specific do you want it? Basically it matches two words consisting of the letters plurandy. The list of names is just a random selection of two part names that only consists of these letters. More specifically it matches: Two groups ({2}), each consisting of a word boundary (\b), followed by a non-empty sequence of the letters plurandy ([plurandy]+), followed by a word boundary (\b), finally followed by an optional space ( ?). [[User:Pmakholm|Pmakholm]] ([[User talk:Pmakholm|talk]]) 09:33, 14 October 2013 (UTC)
::Also, the /'s on the end delimit the regex proper, and the `i` on the end denotes case insensitivity. --[[Special:Contributions/75.66.178.177|75.66.178.177]] 09:39, 14 October
2013 (UTC)
:::In the explanation of how the regex works after the explanation "'''the {2} on the end means to repeat the pattern, so it must match exactly twice'''" I think you need an explanation of how the optional space in the middle interacts with the word boundaries. I.e.
::::(\b[plurandy]+\b ?){2}
:::Expanding:
::::\b[plurandy]+\b ?\b[plurandy]+\b ?
:::Now the optional space at the end is redundant, and the space in the center is not optional, since if there is no space the word boundaries do not exist. If the space is present the word boundaries are redundent because letter space letter sequence always matches them.
::::\b[plurandy]+ [plurandy]+\b ?
:::And this now closely matches the text description "'''Overall, it matches two words separated by a space, composed entirely of the letters in [plurandy], which is what all the names listed have in common.'''" --[[Special:Contributions/108.17.2.71|108.17.2.71]] 17:26, 16 October 2013 (UTC)
:Some examples
:* "Ru Paul" would match, because it is two sequences, each containing only capital or lowercase versions of the listed letters.
:* "Randall Flagg" would not match, because the letters F and G are not in the bracketed list.
:* "Aura Anaya Adlar" would not match; even though the letters are all in the list, there are more than two sequences.
:Hope this helps!
:[[User:Swartzer|Swartzer]] ([[User talk:Swartzer|talk]]) 20:24, 15 October 2013 (UTC)
[[Special:Contributions/209.132.186.34|209.132.186.34]] 09:26, 14 October 2013 (UTC)

I do not think Randal would make such mistake, he would probably use \< \> anyway... unless, he wants us
to think he did mistake, or that backslash was eliminated in html/javascript... thus poining ut to
source code of the page... is there something interesting?
: I skimmed over the source and didn't see anything unusual. The '\'s are absent from the source too. I think it's just that Randall (or a tool he's using) was so affraid of [[327|Bobby Tables]] that he stripped all backslashes from the alt text. {{unsigned|Jahvascriptmaniac}}
::The title text at xkcd.com now has the missing backslashes. Do you normally update the comic here to reflect updates?--[[Special:Contributions/108.17.2.71|108.17.2.71]] 16:14, 14 October 2013 (UTC)
:::Already updated. You were saying?

Can someone explain to me where "In their view, if some humans are born more capable of satisfying their desires than other people, they deserve to reap greater rewards from life than others" comes from? I'm somewhat familiar with objectivist philosophy and I've never heard this put forward as an actual principle. [[Special:Contributions/50.90.39.56|50.90.39.56]] 14:14, 14 October 2013 (UTC)
:Objectivism is the target for much scorn and ridicule in the intellectual world, for its being an inconsistent philosophy that has the sole objective of justifying selfishness and elevating it towards moral righteousness. It's used as the basis for libertarian thought and other radical capitalist economical theories and political stances which promote shameless exploitation (and this attracts further hatred). Randall is no exception to this trend of detractors, and I'd say rightfully so. Ayn Rand's writings are particularly awful, both aesthetically and content-wise, yet in the US a relatively large group of philosophers still adhere to her maxims and the debate continues.{{unsigned ip|37.221.160.203}}

Most people would write the regexp as /(\b[adlnpruy]+\b ?){2}/i. Using "plurandy" makes it look like a word, which is more confusing than using the letters' natural order. --[[User:Ralfoide|Ralfoide]] ([[User talk:Ralfoide|talk]]) 15:58, 14 October 2013 (UTC)

Would it be better to identify Alan Alda not for his role as Hawkeye Pierce in MASH, but for his role in The West Wing as Arnold Vinick, a fiscally-conservative Republican presidential candidate? [[Special:Contributions/193.67.17.36|193.67.17.36]] 16:03, 14 October 2013 (UTC)

:Depends, are we trying to remind him to general audience (I think MASH is more known) or find out why he was included in list? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 08:50, 16 October 2013 (UTC)

There is probably an additional joke or three in that the regex is the minimum needed to capture the first three names together (hinted at by "plurandy" eg plural rand) , but also captures the others. on top of which all of the listed people are considered "intrinsically better" (by virtue of fame if nothing else)[[Special:Contributions/74.213.201.51|74.213.201.51]] 03:14, 15 October 2013 (UTC)

Alan Ladd may have been a founding member of the Secret Council of /(\b[plurandy]+\b ?){2}/i. [[Special:Contributions/71.190.237.117|71.190.237.117]] 07:15, 15 October 2013 (UTC)

It's probably obvious to most programmers, but is it worth pointing out that part of the pun is that the random number generator function is called rand() in most C-family languages? [[Special:Contributions/130.60.156.183|130.60.156.183]] 14:07, 15 October 2013 (UTC)

Another member of this secret society is Randall P [[Special:Contributions/79.182.178.53|79.182.178.53]] 16:45, 15 October 2013 (UTC)

From above: "Objectivism is the target for much scorn and ridicule in the intellectual world, for its being an inconsistent philosophy that has the sole objective of justifying selfishness and elevating it towards moral righteousness. It's used as the basis for libertarian thought and other radical capitalist economical theories and political stances which promote shameless exploitation (and this attracts further hatred). Randall is no exception to this trend of detractors, and I'd say rightfully so. Ayn Rand's writings are particularly awful, both aesthetically and content-wise, yet in the US a relatively large group of philosophers still adhere to her maxims and the debate continues." OK, but a few comments: All philosophies are inconsistent when looked at closely enough, refer Godel and others. Others do not see the inconsistency in Objectivism quite so plainly as in the quoted comment. Ayn Rand and Objectivism are not "the" basis of libertarian thought, there are far more highly thought of libertarian thinkers, a list of whom should come readily to mind to any of those occupying "the intellectual world" (sic), whether or not they have sympathy with libertarian ideas. It is also unfair to characterise Objectivism as having as its "sole" objective that as stated. Further, as a general principle, one ought not to take someone poking fun at a concept as *proof* that they are quite as opposed to it as you are. Now, whereas I would not categorise myself quite as a fellow traveller, a much fairer view of Objectivism is found at WP: http://en.wikipedia.org/wiki/Objectivism_(Ayn_Rand) [[Special:Contributions/81.135.136.159|81.135.136.159]] 11:22, 16 October 2013 (UTC)

:Other philosophies are no more consistent, agreed. But other philosophies do not claim perfect "objective" consistency as their fundamental principle. Attacking Objectivism/Objectivists for lack of internal consistency--or for not recognizing that at some, very fundamental, level it is all stacked on top of some assumptions (just like every other philosophy, and even the scientific method)--is the equivalent of attacking Christianity/Christians for lacking compassion and forgiveness. [[Special:Contributions/129.176.151.14|129.176.151.14]] 14:04, 16 October 2013 (UTC)

:Poking fun can indeed fall into the categories of self-irony or goodwill, but in this case Randall quite explicitly accuses the recipient of bias, making his disapproval pretty unequivocal. [[Special:Contributions/199.48.147.40|199.48.147.40]] 16:51, 16 October 2013 (UTC)

I have added a line about the rational numbers joke; it's definitely there, though I'm not sure if Randall intended it (probably did?). {{unsigned ip|76.124.119.161}}
:Don't think it makes much sense, because a random number generator algorithm of any kind couldn't possibly generate irrational numbers in finite time. [[Special:Contributions/77.244.254.228|77.244.254.228]] 16:34, 17 October 2013 (UTC)
: It does make sense, mathematically speaking a random number chosen in any open interval is irrational with probability 1, and yet any open interval contains rational numbers that could, in principal, be chosen due to density of the rationals. The joke is brilliant, if intended. [[Special:Contributions/76.124.119.161|76.124.119.161]] 04:00, 18 October 2013 (UTC)
::Yes but, at that point, all random number generators are biased and not just the Ayn Random number generator. Also, the bias towards rational numbers doesn't seem to be there when your pool of numbers is just the rationals. The whole idea behind the joke seems to be more like Ayn Rand's assumptions of objectivity ending up favoring certain social groups. I dunno, it just seems forced to me. [[Special:Contributions/220.117.150.36|220.117.150.36]] 19:00, 18 October 2013 (UTC)
::: Considering real numbers are well-understood mathematically this seems like a shortcoming of implementation, which isn't that interesting... the concept is there. [[Special:Contributions/76.124.119.161|76.124.119.161]] 22:06, 18 October 2013 (UTC)
:::: The whole idea behind random number generation bias is the bugs they can create within software implementation (for example, weakening cryptography). An hypothetically generated irrational number would have to be truncated at some decimal place (thus making it rational) for it to be usable. Here it's a programming joke, not a math one. [[Special:Contributions/95.229.229.31|95.229.229.31]] 22:37, 18 October 2013 (UTC)
::::: ...unless interpreted as a math joke. I agree that the joke admits programming interpretation, but I'd never try to exclude other interpretations as well. The math interpretation is valid since one can choose not to get muddled in implementation and to instead envision a hypothetical random number generator not bound by truncation. Randall's comics certainly admit this kind of whimsy. [[Special:Contributions/76.124.119.161|76.124.119.161]] 23:55, 18 October 2013 (UTC)
:::::: Well, it says "This Ayn Random number generator you wrote" so I'd take it at face value, but that's just me. [[Special:Contributions/95.229.229.31|95.229.229.31]] 00:33, 19 October 2013 (UTC)

And somehow, no one's mentioned the classic cartoon ''[[221]]:Random Number'', which presents a random number generator which is heavily biased towards one number. [[User:JamesCurran|JamesCurran]] ([[User talk:JamesCurran|talk]]) 21:58, 17 October 2013 (UTC)

Is the joke here not along the lines that Ayn Rand's politics, and that of Libertarianism, claim that they are fair and that they treat everyone equally - in that, supposedly, anyone can get what they want and be successful if they work hard - but the reality is that some people will fare better than others due to having certain advantages such as having been born into wealth, knowing the right people, one might even suggest that being white, middle class and male are advantageous. In a random number generator you would expect any number to be as likely to come up as any other. Similarly, Rand supporters would argue that under Objectivism, any person is by default as able to be successful as any other. The fact that some people succeed and others fail is explained as some people being inherently more able to succeed, rather than any bias in the system itself - hence she divides people into 'looters' and 'moochers'; there's also that scene I always remember in Dirty Dancing where the guy chucks a copy of The Fountainhead in Baby's direction and says 'some people count, some people don't'. Randall is mocking the idea of a system that is supposedly inherently fair and yet biases certain classes of people, with the idea of a 'random' number generator that is biased towards certain numbers not because of a problem with the system but because some numbers are supposedly 'inherently better'.[[Special:Contributions/213.86.4.78|213.86.4.78]] 15:09, 21 October 2013 (UTC)

1274: Open Letter

2013-10-07T11:26:47Z

213.86.4.78: /* Explanation */

{{comic
| number = 1274
| date = October 7, 2013
| title = Open Letter
| image = open_letter.png
| titletext = Are you ok? Do you need help?
}}

==Explanation==
{{incomplete}}
Under some circumstances, the United States Federal Government {{w|Government_shutdown_in_the_United_States|can temporarily shut down}} pending budget legislation from the United States Congress. These shutdowns are typically due to political disagreements between the President, the House of Representatives, and the Senate.

Over the years, various conspiracy theories have been proposed claiming that the United States Government is not controlled by publicly-elected officials, but rather by one or more organizations that secretly control the actions of the government (sometimes termed a {{w|Shadow_government_(conspiracy)|"shadow government"}}).

[[Randall]] jokes on the {{w|United_States_federal_government_shutdown_of_2013|US government shutdown in 2013}}, that has been ongoing for a week and is still current as of the time of this comic, by writing a letter to the shadow government, telling them that this situation is embarrassing and asking them to fix the problem.

This comic may also be subtly arguing against the plausibility of the aforementioned conspiracy theories if one assumes that a shadow-controlled government would be more likely to operate with a singular purpose and therefore be less susceptible to paralyzing political disagreements. That is to say, if an outside organization were controlling the US government, then it would demonstrate more competence than the US government is currently exhibiting. Randall previously alluded to this in the title text to [[1081|comic 1081]]: "Really, the comforting side in most conspiracy theory arguments is the one claiming that anyone who's in power has any plan at all." This is one of several comics in which Randall expresses dismay at how many intelligent people can fall for absurd conspiracy theories; see comics [[258]] and [[690]], among others.

The title text plaintively asks if the conspiracy masters are experiencing some sort of personal problem that is interfering with their ability to smoothly run the government from behind the scenes.

=== List of addressees ===
{| class="wikitable"
|-
! Addressee !! Brief Description
|-
| {{w|Freemasonry|The Freemasons }}|| Fraternity claiming the legacy of medieval stonemasons. Organised in local groups, the so called ''Lodges''.
|-
| {{w|Illuminati}} || Secret society formed in Bavaria to further the ideas of {{w|enlightenment}}. Although officially banned in 1785, many conspiracy theorists believe the organisation might have survived and is still secretly exerting influence.
|-
| {{w|Church of Scientology|Scientology}} || Self-proclaimed church founded by science-fiction writer {{w|L. Ron Hubbard}}. Often criticised for alleged {{w|brainwashing}} of its members and accused of hiding commercial interests behind religious claims.
|-
| {{w|Federal_Emergency_Management_Agency|FEMA}} || Agency of the United States Department of homeland security, that has been granted extensive authorisations in cases of emergency and is therefore believed to act as an entity independent of governmental control.
|-
| {{w|New_World_Order_(conspiracy_theory)|The New World Order}} || Not a secret organisation itself, but rather the concept of establishing a totalitarian system controlled by any elitist group in this list.
|-
| {{w|Federal_Reserve_System|The Federal Reserve}} || Central state bank system of the United States, therefore to some degree able to control the monetary circulation of the {{w|US Dollar}}.
|-
| {{w|Citigroup}} || One of the largest [http://www.fool.com/investing/general/2013/06/26/citigroup-wants-to-rule-the-world.aspx multinational banks], most of which are rumored to have [http://dealbook.nytimes.com/2006/07/25/drevil-wounds-citigroup/ nefarious purposes].
|-
| {{w|Halliburton}} || One of the largest government contractors, formerly run by Dick Cheney.
|-
| {{w|Google}} || One of the largest DotCom corporations. Google's public motto is "don't be evil". The idea of secret plans of Google has been mentioned in comic [[792]].
|-
| {{w|Vatican|The Vatican}} || The Pope and his inner circle, who control the Roman Catholic Church. The Church was a major political power in Western Europe before the rise of {{w|secularism}}, and still wields considerable influence.
|-
| {{w|Bilderberg_Group|Bilderburg}} || The Bilderberg Group. An private conference of about 120-140 invited guests -- mostly bankers, politicians, and directors of large corporations -- from North America and Europe, which meets every year to discuss international issues.
|-
| {{w|Walmart}} || The largest retail superstore, not above [http://google.com/search?q=walmart+mexico+bribery using bribery to get its way].
|-
| {{w|Rothschild_family|The Rothschilds}} || Family of Jewish financiers that was later elevated into European nobility. Believed to exercise influence through considerable wealth.
|-
| {{w|Knights_Templar_(Freemasonry)|The Knights Templar}} ||
|-
| {{w|High_Frequency_Active_Auroral_Research_Program#Conspiracy_theories|HAARP}} ||
|-
| {{w|United_Nations|The UN}} || The United Nations. Very large intergovernmental organization, formed to prevent and stop wars, offer humanitarian aid, and generally promote cooperation between nations. Most countries in the world are members. It has a lot of influence, but little direct power unless its member states choose to cooperate.
|-
| {{w|Skull_and_Bones|Skull & Bones}} || A secret society at Yale University. Both George W. Bush and John Kerry are members.
|-
| {{w|Bohemian_Grove|Bohemian Grove}} ||
|-
| {{w|Political_activities_of_the_Koch_brothers#Political_activity|The Koch Brothers}} || Two wealthy brothers who provide funding to conservative causes and are a frequently-cited bugaboo among liberals.
|-
| {{w|Soros_György|George Soros}} || A wealthy financier who provides funding to liberal causes and is a frequently-cited bugaboo among conservatives.
|-
| {{w|Sovereign_Military_Order_of_Malta|The Knights of Malta}} ||
|-
| {{w|Council_on_Foreign_Relations|The CFR}} ||
|-
| {{w|ExxonMobil|Exxon Mobil}} || An oil company; one of the world's largest coroporations.
|-
| {{w|Zionism|The Zionists}} || Zionism is the political movement favoring the creation of a Jewish homeland, a goal achieved with the creation of the state of {{w|Israel}}. In a conspiracy-theory context, it references the belief that wealthy and powerful Jews (such as the above-referenced Rothschilds) control political and social institutions.
|-
| {{w|Vril#Vril_society|The Vril Society}} ||
|-
| {{w|Reptilians|The Lizard People}} || Secret snake-men, similar to the aliens from {{w|V (TV series)}}. This is probably a reference to the conspiracy theories of {{w|David Icke}}, which include the idea that an ancient race of god-like, shapeshifting Lizards have interbred with humans, and that these half-bloods now secretly control the world.
|-
| and everyone else who secretly controls the {{w|Federal_government_of_the_United_States|US Government}} ||
|}

==Transcript==
:[The picture shows a letter.]
:October 7th 2013
:To: The Freemasons, the Illuminati, Scientology, FEMA, the New World Order, the Federal Reserve, Citigroup, Halliburton, Google, the Vatican, Bilderburg, Walmart, the Rothschilds, the Knights Templar, HAARP, the UN, Skull & Bones, Bohemian Grove, the Koch Brothers, George Soros, the Trilateral Commision, the Knights of Malta, the CFR, Exxon Mobil, the Zionists, the Vril Society, the Lizard People, and everyone else who secretly controls the US government
:Can you please get your shit together?
:This is embarrassing.
:Sincerely,
:A Concerned Citizen

{{comic discussion}}

[[Category:Politics]]

Talk:1268: Alternate Universe

2013-09-23T10:38:13Z

213.86.4.78:

I thought Earth Prime was a reference to Sliders... but Wikipedia says it's been used much more widely. [[User:Saibot84|Saibot84]] ([[User talk:Saibot84|talk]]) 04:40, 23 September 2013 (UTC)

Wait, wait ... only "some of you" change your clocks? In the universe I just came from, MOST of them changed their clocks at unsynchronized times for no good reason anyone has ever been able to demonstrate. Only the Third World along with Hawaii and Saskatchewan were holdouts where I came from.{{unsigned ip|72.68.9.56}}

Neither India nor China are having this obscure idea of occasionally changing their clocks for no obvious reasons. So even "most" might be a bit of a stretch. [[User:Pmakholm|Pmakholm]] ([[User talk:Pmakholm|talk]])

Iceland (definitely NOT Third World) does not changes its clocks. It remains on GMT throughout the year, despite being way west of the Greenwich Meridian [[Special:Contributions/95.131.110.106|95.131.110.106]] 09:53, 23 September 2013 (UTC)

Yeah I think it's a Sliders reference. Randall says he was transported in the late 1990s and Sliders aired from 1995-2000. [[Special:Contributions/184.56.86.168|184.56.86.168]] 06:02, 23 September 2013 (UTC)

:Didn't we already had discussion about Earth Prime on [[1184:_Circumference_Formula]]? Hmmm ... should we prepare category for comics mentioning Earth Prime? :-) -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 10:02, 23 September 2013 (UTC)

They eat spiders in some parts of this world, e.g. Cambodia. [[User:Geevade|Geevade]] ([[User talk:Geevade|talk]]) 06:54, 23 September 2013 (UTC)

Reminds me a little bit of this Married to the Sea strip: http://www.marriedtothesea.com/index.php?date=111008 [[Special:Contributions/213.86.4.78|213.86.4.78]] 10:38, 23 September 2013 (UTC)

Talk:1252: Increased Risk

2013-08-20T15:15:32Z

213.86.4.78:

I think this is to address the old chestnut of "<something> will ''double'' your risk of getting cancer!", or the like, where the risk of getting that cancer (in this example) is maybe 1 in 10,000, so doubling the risk across a population wouldmake that a 1 in 5,000 risk to your health... which you may still consider to be an acceptable gamble if it's something nice (like cheese!) that's apaprently to blame and you'd find abstinence from it gives a barely marginal benefit for a far greater loss of life enjoyment. Also, this sort of figure almost always applies towards a ''specific form'' of cancer, or whatever risk is being discussed, meaning you aren't vastly changing your life expectancy at all. In fact, the likes of opposing "red wine is good/bad for you" studies can be mutually true by this same principle (gain a little risk of one condition, lose a little risk from another). (Note: I don't know of any particular "cheese gives you cancer!" stories doing the rounds, at the moment. I bet they have done, but I only mention it because I actually quite like cheese. And I probably ''wouldn't'' give it up under the above conditions.)

It's also possible that this covers the likes of "<foo> in <country> is 10 times more dangerous than it is <other country>" statements. Perhaps ''only'' ten incidents happened in the former, and a single instance in the latter, out the ''whole'' of each respective country. Or a single incident occured in both, but the second country is ten times the size, so gets 'adjusted for population' in the tables. And, besides which, that was just for one year and was just a statistical blip that will probably revert-towards-the-mean next year.

Finally, for a given risk of some incident happening on the first two trips, with no 'memory' or build-up involved, it pretty much is half-as-likely-again for the incident to have happened (some time!) in three separate trips. (Not quite, if those that lose against the odds and get caught by the incident the first or second trip never get to ''have'' a (second or) third trip... but for negligable odds like thegiven example, of the dog with the handgun, it's near-as-damnit so.) [[Special:Contributions/178.104.103.140|178.104.103.140]] 11:12, 16 August 2013 (UTC)

Where did "dogs with shotguns" come from? I only saw "handgun" in the comic. Besides, I interpreted the risk as being hit by a negligent discharge from the handgun, not being deliberately attacked by the dog. Also, since probabilities are the set of real numbers between 0 and 1 inclusive, there are an uncountable number of them. "A x% increase in a tiny risk is still tiny" is an inductive statement, which means it could only be used to argue that a countable set of numbers is tiny. [[Special:Contributions/76.64.65.200|76.64.65.200]] 12:24, 16 August 2013 (UTC)

:If induction base is uncountable, you can prove it for the whole [0; 1]. For example your induction base may be "every risk under 0.00000000000000000001% is tiny". --[[User:DiEvAl|DiEvAl]] ([[User talk:DiEvAl|talk]]) 12:38, 16 August 2013 (UTC)

::Aha you caught me. I also realized that if a number is tiny, any number smaller than it is also tiny. So if we can prove that 1 is tiny, then we can prove that all numbers between 0 and 1 (known as probabilities) are tiny. [[User:Diszy|Diszy]] ([[User talk:Diszy|talk]]) 15:46, 18 August 2013 (UTC)

I think it's worth mentioning that this comic doesn't [[985|distinguish between percentages and percentage points]]. --[[User:DiEvAl|DiEvAl]] ([[User talk:DiEvAl|talk]]) 12:35, 16 August 2013 (UTC)

Is it the case that doing something three times increases risk by 50% over two times inherently? I feel like this is the case, but it's early, here. Also, I'm not sure Randall is attacked by a dog, he may be using it as a diversion. I think that he's done this before. [[User:Theo|Theo]] ([[User talk:Theo|talk]]) 12:56, 16 August 2013 (UTC)
:(First, good point, DiEvAl, about the percentages/percentage-points. I ''knew'' I'd missed something out in my first thoughts. I actually tend to assume ''against'' percentage points, which is somewhat the opposite from what I've seen in the general public.)
:Actually, depends on how you count it. But I was using the "encounter 'n' incidents per trip", "encounter '2n' incidents per two trips", "encoutner '3n' incidents per three trips" measure, where 3n==2n+50%. But that works best with a baseline of >>1 incidents per trip assumed. In reality, if the chance is a fractional 'p' for an occurance in one instance, it's (1-p) that it ''didn't'' occur thus (1-p)n that it didn't occur in any of 'n' instances and 1-(1-p)n that it did (at least once, possible several times or even all). Not so simple, but for p tending to zero it 'does' converge on 1.5 times for across three what you'd expect for two (albeit because 0*1.5=0). Like they say, "Lies, Damn Lies...", etc. ;) [[Special:Contributions/178.104.103.140|178.104.103.140]] 14:22, 16 August 2013 (UTC)

I don't think Randall is being attacked by a dog at all. What he's saying is that if you are going to think getting attacked by a shark is so likely, then you better be watching out for that never-gonna-happen dog scenario too. [[User:Jillysky|Jillysky]] ([[User talk:Jillysky|talk]]) 13:56, 16 August 2013 (UTC)

Is 0.000001% really "one in a million"?
;If 1% = 1 in 100, then
:0.1% = 1 in a 1,000
:0.01% = 1 in a 10,000
:0.001% = 1 in a 100,000
:0.0001% = 1 in a 1,000,000
:0.00001% = 1 in a 10,000,000
:'''0.000001% = 1 in a 100,000,000'''
Would it be more accurate to leave off the % sign?
Assuming I'm right, I think it'd be less confusing to leave it and reduce the numbers by a couple orders of magnitude.
--Clayton [[Special:Contributions/12.202.74.87|12.202.74.87]] 14:36, 16 August 2013 (UTC)

''If the chance of the dog attack is 0.000000001% (one in a billion) on each visit to the beach, then the chance of attack over two visits is 0.000000002% whereas in three visits it becomes 0.000000003%''

Um, no. Following that logic, if I go to the beach a billion times then I '''will''' get shot by a dog that is packing. Rather, each visit to the beach has it's own odds, like the rolling of dice? On any particular visit there's a one-in-a-billion chance. And that's true on each subsequent visit as well. Tuesday's visit to the beach isn't twice as dangerous just because I was at the beach on Monday. [[User:CFoxx|CFoxx]] ([[User talk:CFoxx|talk]]) 16:26, 16 August 2013 (UTC)
:For each visit that is the case. Because it's one visit, that's true. However, if (time not being a factor) one were to have a billion visits planned, the odds over all would be increased. Pretty sure that overall this means that you got the joke faster than I did. Thanks for the clarification! [[User:Theo|Theo]] ([[User talk:Theo|talk]]) 17:06, 16 August 2013 (UTC)
::The odds overall may increase with multiple visits. But not, at least, at the rate listed. Otherwise that billionth trip (if one survived that long as one is likely to do) would be certain death. [[User:CFoxx|CFoxx]] ([[User talk:CFoxx|talk]]) 17:30, 16 August 2013 (UTC)
:::Correct. Technically, the odds we are worried about are the "probability of being shot one or more times by a dog". So if the probability is 1/10^9 for any given day, than the odds of not being shot are (10^9-1)/10^9 for any given day, and the odds of not being shot over three days are (10^9-1)^3/10^27, and then the odds of being shot one or more times are 1-((10^9-1)^3/10^27), which is roughly 2.999999997000000001/10^9. That is close, but slightly less, than 3/10^9. [[Special:Contributions/206.174.12.203|206.174.12.203]] 18:01, 16 August 2013 (UTC)Toby Ovod-Everett
::::Absolute incorrect: You always have to look at the single event. More events do not belong together, you always have the same probability at each single event. So, even 10 billion events may or may NOT result in a disaster. Math isn't easy.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 19:17, 16 August 2013 (UTC)
:::::I believe what CFoxx was saying is that if the odds of something happening on any given day are one in three, then the odds of that thing happening at least once during a four day period is NOT 4/3rds! I was pointing out that the proper way to calculate the odds for a four day period is to say that the odds of it not happening on any given day are two in three. You take that probability and raise it to the fourth power, giving the odds that it won't happen at all during a four day period of 16/81, thus the odds that it will happen during that four day period is 65/81. I then did that same calculation for the 1 in a billion chance per day and applied it to the three day period, and recognized that he was correct that the true probability of the event happening one or more times over a three day period was not three times the probability of it happening on any given day, but also noted that the difference for a 1 in a billion chance over a small period is pretty close to the simplistic (but incorrect) approach. My rough estimate for the "one in a billion per day" event happening one or more times during a billion day period is 63.21%.[[Special:Contributions/206.174.12.203|206.174.12.203]] 21:33, 16 August 2013 (UTC)Toby Ovod-Everett
::::::Wow, we still have many great scientists here!--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 21:46, 16 August 2013 (UTC)
::::::THANK YOU, Toby! [[User:CFoxx|CFoxx]] ([[User talk:CFoxx|talk]]) 18:09, 17 August 2013 (UTC)

Just a thought: is the title text a reference to the Sorites paradox? --AJ [[Special:Contributions/80.42.221.105|80.42.221.105]] 17:25, 16 August 2013 (UTC)

Rats! I made the newbie mistake of editing something before I found the discussion page. I looked for it, honest I did! I see that UTC has already brought up what I referred to as "Cueball's error" in my (pre-log-in) edit. I did find it hard to believe I'd be the first xkcd fan to notice this error. I think this is worth addressing in the explanation, though I of course won't take offense if someone wants to obliterate my edit and start over. (CLSI){{unsigned|CLSI}}

Maybe he means this: Florida man shot by his dog, police say http://usnews.nbcnews.com/_news/2013/02/26/17107343-florida-man-shot-by-his-dog-police-say?lite{{unsigned|Jb}}

Saying that unfortunately Cueball is mistaken in his calculations because he said 50% instead of 49.99999992% is a bit of an exaggeration. [[User:Xhfz|Xhfz]] ([[User talk:Xhfz|talk]]) 20:19, 16 August 2013 (UTC)

;Chaos at explain section
Please stop adding this, it does not explain the comic, it only belongs to this discussion page:

:Note that the 50% figure is an approximation. Assuming the odds of being attacked by a dog is ''x'', the odds of being attacked by a dog at least once in two visits is 1 - (1-''x'')2. The odds of being attacked at least once in three visits is 1 - (1-''x'')3. Therefore, if one visit has one in a billion probability of attack, then two visits have not 2 in a billion, but 1.999999999 in a billion. Similarly, three visits have a probability of 2.999999997 in a billion. Saying 50% instead of 49.99999992% is a reasonable approximation.

:Unfortunately, [[Cueball]] is mistaken in his calculations. This is easier to see with an event that has greater probability, such as a coin toss. Assuming the odds of getting heads in one flip is .5, the odds of getting heads at least once in two flips is .75 (i.e., 1 minus [.5 X .5], the odds of getting tails both times), and the odds of getting heads at least once in three flips is .875 (1 minus [.5 X .5 X .5], the odds of getting three tails in a row). Getting heads in three flips is not 50% more likely than getting heads in two flips. With very low probabilities (such as the probability of attack by a dog swimming with a handgun), Cueball's calculation gives an extremely close approximation of the actual probability, but one can't apply the same logic to events of just any probability.

::Cueball says *statistically* the risk of some bizarre event increases 50%. This is essentially correct as many have pointed out that 49.99999999 is not really statistically different than 50. What is likely bothering a lot of people (including myself) is that the explainxkcd description states "If the chance of the dog attack is one per billion on each visit to the beach, then the chance of attack over two visits *is* two per billion whereas in three visits it *becomes* three per billion." There are no weasel words like "approximately", "about", "around", etc. This reminds people of flatly incorrect uses of probabilities like the one you describe. But surely the probability of getting heads from a fair coin toss is not on a similar order of magnitude as the probability that a swimming dog shoots someone with a handgun. [[User:S|S]] ([[User talk:S|talk]]) 00:40, 17 August 2013 (UTC)
:::''What is likely bothering a lot of people (including myself) is that the explainxkcd description states "If the chance of the dog attack is one per billion on each visit to the beach, then the chance of attack over two visits *is* two per billion whereas in three visits it *becomes* three per billion." There are no weasel words like "approximately", "about", "around", etc.'' '''Exactly.''' Explanations here have been very helpful in explaining some of the more scientific aspects of things Randall includes. Noting this one makes a (albeit slight) mistake in that regard is appropriate. (And the irony of incorrectly using probabilities in explaining a comic about how people do that is amusing.) [[User:CFoxx|CFoxx]] ([[User talk:CFoxx|talk]]) 18:15, 17 August 2013 (UTC)

I had to think of http://xkcd.com/1102/ when reading the first paragraph of the explainxkcd description. (The context is different, but the dubious use of percentages is the same.) [[User:S|S]] ([[User talk:S|talk]]) 00:40, 17 August 2013 (UTC)

;Proof
I believe Cuball's calculation is way off. The odds of a dog attack should increase by 50% when looking at two beach trips rather than one. But the odds of an attack occurring with 3 visits should only increase by about 16.67%. This can be seen by analyzing a fair dice roll or a coin toss. Unless I am missing something, even with extremely small probabilities, this will hold. Can anyone write a proof to show otherwise?{{unsigned ip|174.98.234.239}}
:As far as I understand it: doing something twice doubles your chance of getting the desired outcome. For example, you want to role a dice and get a six. If you role it twice, you have double the chance of getting at least one six. If you role it three times you have triple the chance of getting a six; in other words you increase it from two chances to three chances, which is an increase of 50%.