Explain xkcd: It's 'cause you're dumb.
In this comic, after hearing about the "Cell Phones Don't Cause Cancer" study, Black Hat plots "Total Cancer Incidence" per 100,000 and "Cell Phone Users" per 100 on the same graph. The graph in frame 3 shows that the number of cell phone users rises after the number of cancer incidence, which makes Black Hat comically come to the conclusion that Cancer causes Cell Phones.
Also, since the image text asks, yes, the way that Black Hat holds the laptop in frame 2 totally makes me cringe.
The comic highlights a well-known fallacy known as post hoc ergo propter hoc, often shortened to simply post hoc. The Latin translates to "after this, therefore because of this," referring to the common mistake that because two events happen in chronological order, the former event must have caused the latter event. The fallacy is often the root cause of many superstitions (e.g., a person noticing he/she wore a special bracelet before getting a good test score thinks the bracelet was the source of his/her good fortune), but it often crosses into more serious areas of thinking. In this case, the scientific research community, which often prides itself on its intellectual aptitude, is gently mocked for being nonetheless prone to such poor reasoning all too often.
- [A person is holding a cellphone. The black hat guy is sitting at a desk with a laptop.]
- Person: Another huge study found no evidence that cell phones cause cancer. What was the W.H.O. thinking?
- Black Hat Guy: I think they just got it backward.
- [The black hat guy swivels in his chair, holding the laptop by the upper edge of the screen.]
- Person: Huh?
- Black Hat Guy: Well, take a look.
- [There is a plot of total cancer incidence and cell phone users. Cancer rises from 1970 to 1990, then stays relatively steady. Cell phone use rises from 1980 to the present.]
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- Person: You're not... There are so many problems with that.
- Black Hat Guy: Just to be safe, until I see more data I'm going to assume cancer causes cell phones.
On first read I thought the joke is that the cell phone graph shape (somewhat) closely mimics the shape of the cancer graph, including the part where it begins to level off - implying that one linearly correlates with the other, with a 20 year delay (a typical time it takes for cancer to manifest, except in this case it's backwards). ultramage 14:17, 22 December 2012 (UTC)
That and the fact the graph is out by a scale factor of 1000 is always a fun way to screw over how the statistics look. 188.8.131.52 (talk) (please sign your comments with ~~~~)
Nah b', it's 2000. 184.108.40.206 (talk) (please sign your comments with ~~~~)
- The real problem with the graph is that it makes it look like cancer rates have increased from near-zero levels to way higher since 1970, until you actually read the Y axis and see that it's gone from about 400 (per 100,000) to about 475. This is an increase of only 18.75%, as opposed to the visual appearance of a 300% increase. Hats off to Black Hat!! 220.127.116.11 01:18, 7 August 2013 (UTC)
I thought the laptop joke was that some people believe not to put it on your lap because it messes with your reproductive organs! ~JFreund
- But you know now you are wrong, correct? 18.104.22.168 06:59, 21 January 2014 (UTC)
- If your laptop starts messing with your reproductive organs, you may want to either tell an adult, or stop taking drugs (or possibly take more drugs). 22.214.171.124 06:45, 3 May 2014 (UTC)
I originally thought that the graph was supposed to show that an increase in cellphone use caused a decrease in cancer. I'm not sure why Randell didn't go with that conclusion, as it seems way more obvious to make when you look at tha graph, and it's humorously the opposite of what people are saying. Still very silly, of course :p Maplestrip (talk) 08:37, 31 October 2014 (UTC)
Why does the title text explanation refer to panel 2? From what I can see the title text either refers to a) you should not hold your laptop by its screen as it may damage it (in panel 2) or b) you should not not rest your laptop on your lap as it may overheat and damage you (in panel 4). I think a) makes more sense since the comic refers to how black hat "holds" the laptop, but I can also see that b) references the subject of the comic. 126.96.36.199 10:19, 22 November 2014 (UTC)
- Seconded. I'm changing it. --188.8.131.52 19:05, 16 December 2014 (UTC)