explain xkcd - User contributions [en]

2283: Exa-Exabyte

2020-03-23T20:54:46Z

172.68.34.190: 1894: Real Estate

{{comic
| number = 2283
| date = March 20, 2020
| title = Exa-Exabyte
| image = exa_exabyte.png
| titletext = To picture 10^18, just picture 10^13, but then imagine you connect the left side of the 3 to close off the little bays.
}}

==Explanation==
{{incomplete|Created by 10 EXA-EXABYTES OF APPLES. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
This is Randall's first comic in over a week not overtly part of his [[:Category: COVID-19|COVID-19 series]]. It could still be a deliberate allusion to the biology and complexity behind the Corona outbreak, or, if not a deliberate allusion, its theme of biological complexity could have been inspired thereby.

This is a comic about the difficulty of picturing or understanding large numbers. As mentioned in the comic, an {{w|exabyte}} is 1018 bytes, while an "exa-exabyte"—not a common word, but one that makes sense if you apply the principles of {{w|metric prefix}}es—is 1036 bytes. 1036 is properly given the name undecillion (in short scale, and sextillion in long scale).
According to [https://www.nytimes.com/2015/07/21/science/counting-all-the-dna-on-earth.html a 2015 article] by ''The New York Times'', researchers estimate that there are about 5 * 1037 DNA {{w|base pair}}s on Earth (50 trillion trillion trillion). So [[Miss Lenhart]]'s claim of 10 exa-exabytes—1 * 1037 bytes is a reasonable approximation ({{w|Fermi estimation}}). (The estimate was 5 plus or minus 4 * 1037. There are 4 possible base pairs, or 2 bits per pair, a byte is 8 bits.)

These numbers are larger than most people can imagine. Even much smaller numbers such as a billion (109) or a trillion (1012) are hard to imagine.{{Citation needed}} For instance:
* 1 billion seconds is equal to 31.7 years; 1 trillion seconds is equal to 31,688.74 years.
* [https://medium.com/@alecmuffett/a-billion-grains-of-rice-91202220e10e 1 billion grains of rice] weigh approximately 34,447 lb (15,625 kg).

Wikipedia has an article on the {{w|exabyte}} and one on large numbers which describes {{w|Orders of magnitude (numbers)#1018|various things close to 1018}}.
[https://abc7news.com/science/possibly-habitable-planet-found-100-light-years-away/5821548/ TOI 700 d], a potentially habitable Earth-like {{w|exoplanet}} is 100 light years away, which is about 1018 meters.

[[Megan]] trivializes the problem away by describing an exabyte as 10 apples, with "18 smaller apples, floating next to them and a little above", representing the notation 1018 using apples for digits. This is entirely unhelpful, as apples, whatever their position, don't represent exponents, and this causes Miss Lenhart to yell out "No!" in frustration. The title text further trivializes the problem of visualizing large numbers by suggesting that you can visualize 1018 as a number by simply visualizing the similar-looking number of 1013 with some extra lines drawn to turn the 3 into an 8. Changes in exponents can cause huge changes in the value shown, and this is no exception: Changing that 3 into an 8 changes the value by a factor of 100,000.

Randall has previously discussed the difficulty of large numbers in [[2091: Million, Billion, Trillion]], [[1894: Real Estate]], and [[558: 1000 Times]].

[[1605: DNA]] also discusses how "hard" biology is.

==Transcript==
:[Miss Lenhart is holding a pointer, and is pointing it towards a blackboard behind her, while she addresses her student Cueball who is sitting on a chair at a desk to the left of her, holding his hands on his knees.]
:Miss Lenhart: Biology is hard because there's so ''much'' of it. Earth hosts about 10 exa-exabytes worth of DNA.

:[In a frame-less panel, the panel has panned to the left and is now showing Miss Lenhart holding the pointer to her side, but without the blackboard. In front of her is now both Cueball and Megan sitting at their desks. Cueball has taken one hand on to the table. Megan has both hands folded on the table in front of her.]
:Cueball: What's an exa-exabyte?
:Miss Lenhart: It's 1036 bytes.
:Cueball: How do I picture '''''that?'''''
:Miss Lenhart: Imagine you had an exabyte of data, but each byte ''contained'' an exabyte of data.

:[Zoom in on Cueball's head. A starburst to the right indicates Miss Lenhart's voice from off-panel.]
:Cueball: I can't even picture what an exabyte is.
:Miss Lenhart (off-panel): It's 1018 bytes.
:Cueball: But how do I picture 1018?

:[Zoomed out to showing Megan, Cueball, and Miss Lenhart along with the blackboard. Megan has raised a hand palm up. Cueball is looking back at her over his shoulders. Miss Lenhart is forming a closed first with her empty hand, the one without the pointer.]
:Megan: Imagine you had 10 apples.
:Megan: Now imagine 18 smaller apples, floating next to them and a little above.
:Cueball: Cool, got it.
:Miss Lenhart: '''''No!'''''

{{comic discussion}}

[[Category: Comics featuring Miss Lenhart]]
[[Category: Comics featuring Cueball]]
[[Category: Comics featuring Megan]]
[[Category: Biology]]

Talk:1901: Logical

2020-03-20T03:00:08Z

172.68.34.190:

Potentially relevant: [http://www.tandfonline.com/doi/pdf/10.1080/00224545.1954.9919125]
Potentially relevant: [https://www.youtube.com/watch?v=VdtwTeBPYQA]
Potentially relevant: [http://www.jstor.org/stable/1821269?seq=1#page_scan_tab_contents]
[[User:Joshupetersen|Joshupetersen]] ([[User talk:Joshupetersen|talk]]) 16:00, 11 October 2017 (UTC)

-- Link 1 points to a 1952 paper which demonstrates that "scientists" live longer with the top 6 occupations being Educators, Lawyers, Engineers, Naturalists, Historians and Inventors ... seems a pretty loose definition of scientist to me. --[[User:Rtanenbaum|Rtanenbaum]] ([[User talk:Rtanenbaum|talk]]) 17:39, 11 October 2017 (UTC)

Added the title text to the explanation and transcript. --[[User:JayRulesXKCD|'''JayRules''XKCD''' ]][[User talk:JayRulesXKCD|what's up?]] 16:06, 11 October 2017 (UTC)

For the record I believe the advantages of using statistics over intuition were thoroughly discussed in the Michael Lewis book [https://en.wikipedia.org/wiki/Moneyball ''Moneyball''], also 538 has done studies comparing statistical approaches to election prediction to political punditry and finally the good old [https://en.wikipedia.org/wiki/Monty_Hall_Problem Monty Hall Problem].[[User:Sturmovik|Sturmovik]] ([[User talk:Sturmovik|talk]]) 16:22, 11 October 2017 (UTC)

"... inconclusive scientific evidence against White Hat's position"? Is "inconclusive" the best you can do? Or did you mean "''only'' inconclusive"? Randall is basically attempting to use an argument from silence against anyone asserting White Hat's basic position (for which there is some very good evidence). It's ironic that to argue against the position requires using the law of non-contradiction; hence is self refuting. [[Special:Contributions/198.41.238.52|198.41.238.52]] 22:41, 11 October 2017 (UTC)
: The joke isn't that rational decision-making is bad, it's that many of those who aggressively espouse the importance of rational decision-making and deride the influence of emotions are rarely as rational and logical in their decision-making as they like to think they are.

:If nothing else, a truly rational thinker would realize that for better or worse people ARE affected by emotional cues and that as such subtly insulting those you're speaking to is not a good way to influence opinions and change decisions.

:And a truly self-aware rational thinker would realize that the vehemence of his later complaints about how people are illogical and emotional might have less to do with the objective importance of rationality and more to do with his own feelings being hurt because his opinions were ignored or derided.

:But surely that doesn't apply to anybody here and any sensation of defensiveness that might occur comes from a place of pure logic and reason, right?[[Special:Contributions/162.158.178.165|162.158.178.165]] 15:42, 17 October 2017 (UTC)

This comic is probably a response to the Nobel prize in economics awarded to Richard Thaler for finding ways to nudge people to decisions that the nudger believes to be more common sense.--[[Special:Contributions/162.158.88.188|162.158.88.188]] 09:23, 12 October 2017 (UTC)

The problem with generalizations is that all of them are idiotic.--[[Special:Contributions/162.158.111.151|162.158.111.151]] 12:14, 12 October 2017 (UTC)
: ... including the one you just used :-). -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 00:49, 13 October 2017 (UTC)
:: *Whoosh!*[[Special:Contributions/141.101.98.172|141.101.98.172]] 11:55, 13 October 2017 (UTC)
::: *Whoosh!* [[Special:Contributions/172.68.34.190|172.68.34.190]] 03:00, 20 March 2020 (UTC)

Talk:2277: Business Greetings

2020-03-06T07:51:04Z

172.68.34.190: Thoughts.

This comic appears to be the only one, ever, that doesn't have mouseover text
[[Special:Contributions/162.158.146.160|162.158.146.160]] 05:15, 6 March 2020 (UTC)
:Maybe our mice are just broken. Purely coincidental, I'm sure. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 05:49, 6 March 2020 (UTC)

Maybe Randall posted it really late, staggered into bed, and will post the alt-text in the morning. I saw text but it was just the comic title. [[Special:Contributions/172.68.34.190|172.68.34.190]] 07:51, 6 March 2020 (UTC)

1827: Survivorship Bias

2020-03-04T21:36:06Z

172.68.34.190: Trump's back? Seriously? He has nothing whatsoever to do with this topic. Stop adding him.

{{comic
| number = 1827
| date = April 21, 2017
| title = Survivorship Bias
| image = survivorship_bias.png
| titletext = They say you can't argue with results, but what kind of defeatist attitude is that? If you stick with it, you can argue with ANYTHING.
}}

==Explanation==
This comic is a parody of entrepreneurial speeches. Entrepreneurial speeches are talks, such as graduation commencements or motivational speeches. The idea behind graduation commencements is that the entrepreneur, having accumulated wisdom and experience in the process of becoming successful, will share his insights and experience to the students, in the hope that they learn lessons that will help them achieve success as well. Companies hire motivational speakers to motivate employees to work hard.

A common theme in these talks is that the entrepreneur succeeded by persisting through hardship, sometimes despite other people telling them they would be better off giving up. They advise students to do the same, and to keep pursuing their dreams even through subsequent failure. While this isn't necessarily bad business advice, this can give students a biased vision of reality, and lead them to imagine that they will succeed as long as they keep trying.

This comic makes a joke about survivorship bias, hence the title. {{w|Survivorship bias}}, or survival bias, is the logical error of concentrating on the people or things that "survived" some process and inadvertently [[#Trivia|overlooking those]] that did not because of their lack of visibility. This can lead to false conclusions in several different ways. The survivors may be actual people, as in a medical study, or could be companies or research subjects or applicants for a job, or anything that must make it past some selection process to be considered further. They may also have "survived" on only some of their attempts.

In this comic [[Hairy]] is giving a talk encouraging people to "never stop buying {{w|lottery}} tickets". This is an unwise investment plan, because the chances of winning the lottery are mathematically very low and the total payout is usually less than the total ticket sales, meaning the expected return from buying a lottery ticket is ([[#Trivia|almost]]) always negative. Survivorship bias applies in this situation since people who eventually win (and, presumably, win more than they've spent on lottery tickets in the time that it took them to win) are much more likely to give inspirational speeches than someone who never won or didn't win enough to make the "investment" worthwhile.

The obvious bad strategy (keep buying lottery tickets) is a metaphor for strategies that successful entrepreneurs recommend (keep persisting and putting money into your start-up); these strategies may be bad on average, but people who pursued them and succeeded are much more likely to be invited and give speeches than people who pursued them and went bankrupt (or people who pursued safer strategies and kept their money), making it appear to students that taking high risks and persisting in the face of expensive failure is the optimal strategy. And those who have done both, are more likely to speak about the successes than the failures and bankruptcies.

[[Randall]] says in the caption below the panel that people should be informed about survivorship bias before hearing inspirational talks from successful people.

The title text says "They say you can't argue with results, but what kind of defeatist attitude is that? If you stick with it, you can argue with ANYTHING." In the comic, the speaker's "result" was winning the lottery. Pointing out the survivorship bias is Randall effectively arguing with results, by pointing out that they were obtained randomly, and that it ignores all the other people who may have (foolishly) followed this same process, but never won the lottery. Taken a step further, one could use the survivorship bias to argue against the results of any process, be it research (Any given research process is bound to produce SOME good results, and since those are the only ones published, it is difficult to determine if the research process itself contributed to the good results), business decisions (Some businesses fail, and others succeed, but since only the successful ones stick around, it can be difficult to determine WHY they failed or succeeded), etc..

==Transcript==
:[Hairy, holding an arm out towards an unseen crowd, is standing on a podium with five large bags around him, each having a dollar sign on it.]
:Hairy: Never stop buying lottery tickets, no matter what anyone tells you.
:Hairy: I failed again and again, but I never gave up. I took extra jobs and poured the money into tickets.
:Hairy: And here I am, proof that if you put in the time, it pays off!

:[Caption below the panel:]
:Every inspirational speech by someone successful should have to start with a disclaimer about survivorship bias.

==Trivia==
*Lottery with '''positive return''':
**When item prizes are donated to a lottery (for charity or advertising purposes), sometimes the value of those items may actually be larger than the total price for all of the lottery tickets, if you otherwise would be willing to pay full price for all the prizes.
**In some lotteries, if the jackpot gets too big -- or goes for too many drawings -- without anyone winning it, the jackpot amount gets "rolled down" and distributed across the lower prize levels. These can have a positive return on average -- but ''only'' on the drawings where the jackpot rolls down. People have formed investment groups to buy hundreds of thousands of tickets to exploit these; several such groups repeatedly profited from Massachusetts's {{w|Massachusetts_Lottery#Cash Winfall|Cash WinFall}} game especially. (The Massachusetts State Lottery has an official report ([http://www.mass.gov/ig/publications/reports-and-recommendations/2012/lottery-cash-winfall-letter-july-2012.pdf PDF, 144 KB]) on how such high-volume betting affected the game.)
*'''Examples''' of survivorship bias:
**Diogenes was shown paintings of people who had escaped shipwreck: "Look, you who think the gods have no care of human things, what do you say to so many persons preserved from death by their especial favour?", to which he replied: "Why, I say that their pictures are not here who were cast away, who are by much the greater number."
**Many people {{w|Public Health Cigarette Smoking Act|were smoking}} back in the 1930-70s, thus almost everyone above 80 either smoked cigarettes or was at least subjected to massive passive smoking during those years. Thus anyone above that age could be claimed to prove that you can live a long life while smoking. But they consist of the small group of people that survived in spite of all the smoke, where large sections of those that would have been 80 today, died from cancer or heart disease caused by smoking, long ago, maybe even before they retired. But since these people are dead and gone many years ago, they do not speak up,{{Citation needed}} and are thus the silent majority that is not heard, which is the problem with survivorship bias.
**During World War II, there was a study of the damage done to aircraft, and the recommendation was to add armor to the areas that showed the most damage. The statistician {{w|Abraham Wald}} noticed that the study didn't take into account aircraft that ''didn't'' return: the holes in the returning aircraft thus represented areas where a bomber could take damage and still return home safely.
**Anything created by an Earth-human in this universe. We think it's because we're special, rather than being special because we're here/we survived.
*In the title text, "defeatist" was originally misspelled as "defeatest". This was later corrected.

{{comic discussion}}

[[Category:Comics featuring Hairy]]
[[Category:Science]]
[[Category:Public speaking]]

Talk:2273: Truck Proximity

2020-02-27T15:17:21Z

172.68.34.190:

Lots of dinosaurs driving equipment on a farm out there: https://www.youtube.com/watch?v=0bUmxUWs1Uk or https://www.youtube.com/watch?v=YmgHz8zBZlk [[Special:Contributions/173.245.52.97|173.245.52.97]] 20:47, 26 February 2020 (UTC)

Being pedantic, those are tractors: https://play.google.com/store/apps/details?id=com.imayi.dinofarmfree&hl=en_US Perhaps dinosaurs driving trucks on farms is a niche just begging to be filled ;-) [[Special:Contributions/172.68.189.127|172.68.189.127]] 06:09, 27 February 2020 (UTC)

Can see a strong argument that Randall got the axes wrong here... [[User:Heylukeatthat|Heylukeatthat]] ([[User talk:Heylukeatthat|talk]]) 21:09, 26 February 2020 (UTC)
:How so? I don't see it... There are people with truck-related hobbies who know more info about trucks than the frequency of their proximity to them might demand; which accounts for the asymmetry in the upper-right cluster. Having kids (especially male children raised with heteronormative socially dimorphic entertainment sets, which frequently adhere to traditional social expectations of "stuff for boys") ''definitely'' increases one's exposure to truck-related topics. What's the case for the axes being reversed?
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 21:30, 26 February 2020 (UTC)
::I just read his comment as suggesting the x and y axes should be swapped, where 'proximity to trucks' should be on the x-axis. I'd agree that conventionally that would make more sense, and it was likely done this way to impact the 'reading order' of the clusters for comic effect. --[[Special:Contributions/162.158.214.88|162.158.214.88]] 22:18, 26 February 2020 (UTC)
:::Don't you know? Having knowledge of trucks causes a physical attraction force between you and the truck. [[Special:Contributions/172.69.34.58|172.69.34.58]] 01:25, 27 February 2020 (UTC)
:::The real issue is that the most proximity (distance 0) is at some random point far away from the center of the coordinate system and the center of the coordinate system is some random distance away from a truck. [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 02:59, 27 February 2020 (UTC)
:::A graph doesn't necessary show that x axis causes y axis. even less when it is mapped on the plane instead of being a line graph. But even line graphs may just show correlation, see [[111: Firefox and Witchcraft - The Connection?]] --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 07:35, 27 February 2020 (UTC)
::Economics graphs often reverse the axes like that. Though in this case, I saw it as correlational rather than explicitly causal, so I didn't even notice.

Wait, has Randall come into possession of ''offspring''? Specifically, of the "between 2 and 5 years of age, assigned male at birth" variety? [[Special:Contributions/162.158.79.35|162.158.79.35]] 22:37, 26 February 2020 (UTC)
:This is what I came here curious about! Or is he just making this observation about some friends/family he spends time with?--[[Special:Contributions/162.158.214.82|162.158.214.82]] 23:11, 26 February 2020 (UTC)

I can think of one job that puts someone into that bottom-right corner: total loss valuation specialists (particularly ones specializing in commercial vehicles). We don't get within a hundred miles of trucks, and yet we know substantially more about them than the people who submit the claims to us do (and sometimes more than the owners do). --[[User:Skyrender|Skyrender]] ([[User talk:Skyrender|talk]]) 02:31, 27 February 2020 (UTC)

Clearly Randall (and other parents) should investigate Dinotrux, which I enjoyed with my kids. [[Special:Contributions/162.158.62.15|162.158.62.15]] 10:40, 27 February 2020 (UTC)

Wait... This is almost a Venn diagram -- does this mean parents of 2 to 5 year olds are not "normal people"? How DARE you, sir! I'm as normal as any other sleep-deprived person! (Well, I guess my sanity is questionable since I consciously and deliberately hang around with preschoolers...) --BigMal // [[Special:Contributions/172.69.68.185|172.69.68.185]] 13:15, 27 February 2020 (UTC)

"Apparently trucks and farms do not mix very well." Seriously? Go spend half an hour listening to country music; that'll disabuse you of that mistaken notion rather quickly! :P