https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=DLJessupexplain xkcd - User contributions [en]2026-05-19T22:20:36ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=1999:_Selection_Effect&diff=1578361999: Selection Effect2018-05-28T19:25:05Z<p>DLJessup: Spelling error</p>
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<div>{{comic<br />
| number = 1999<br />
| date = May 28, 2018<br />
| title = Selection Effect<br />
| image = selection_effect.png<br />
| titletext = fMRI testing showed that subjects who don't agree to participate are much more likely to escape from the machine mid-scan.<br />
}}<br />
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==Explanation==<br />
{{incomplete|edited by an fMRI machine escapee! (help! get me out of here) - Please change this comment when editing this page. Do NOT delete this tag too soon.}}<br />
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The title refers to the effect in scientific fields where the people who agree to work with a researcher can affect the outcome. For example if I said I wanted to do a study on an embarrassing condition, people who know they have it might be more apprehensive and thus not participate. This can skew the results to say that the condition is rarer than it is.<br />
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Ponytail says that people who agree to be in a study at their lab are less likely to attempt to escape. This makes sense, since if you agreed to the study, you know why you are there, while if you didn't, you may have been kidnapped. This implies that Ponytail has recently kidnapped people for a study, and that most of the people she kidnapped called the police, as one should do when being kidnapped{{Citation needed}}.<br />
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The title text says that people who didn't agree to go inside an MRI machine are more likely to escape the machine mid-scan. Again, this makes sense, because being put somewhere against your will makes you unsure what is going on, making you try to find a way out.<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Ponytail stands on a podium giving a presentation in front of a chart with some boxplots.]<br />
:Ponytail: Our research shows that compared to the overall population, people who agree to participate in scientific studies are significantly less likely to call the police to rescue them from our lab.<br />
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{{comic discussion}}<br />
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[[Category:Comics featuring Ponytail]]<br />
[[Category:Science]]</div>DLJessup