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There are several internet pages that claim that the number of serial killers born in November is particularly high.

For example, this article lists eleven murderers born in November and quotes a website "UberFacts":

Seventeen serial killers were born in November, compared with an average of nine for other months, out of a total of more than 100 in the study.

Similarly, the top-voted answers to this Quora question, which asks why there are so many serial killers born in November, accept the claim implied in the question (i.e. that the number of serial killers born in November is indeed unusually high), and present explanations along the lines of the arguments presented in Maxwell Gladwell's 2008 book "Outliers" for the uneven distribution of professional hockey players' months of birth. Due to the way children are assigned to grades in schools based on their age in the American educational system, the top-voted Quora answers argue that children born in September, October and November are going to be the youngest member of their grades. Due to the resulting age difference, the answers claim that they are more likely to become potential targets of bullying, or sets them at a learning disadvantage in the educational system. In turn, this is presented as a reason for the large number of serial killers born in November.

However, not all sources discussing correlations between month of birth and the number of serial killers agree that November is indeed the month with the highest number. For example, this article questions the number of 17 serial killers born in November, and argues that twice as many serial killers were born in May:

The internet figure suggests that 17 ‘serial killers’ were born in the month of November, but that’s very contentious. Taking the established definition of ‘serial killer’ there are only 8 at best -does the repugnant Derrick Bird even qualify as a serial killer?

What’s far more interesting is that one month alone has almost double the number of serial killers than the spurious 8 of November, yet stripped of spooky Scorpio connotations and exposed in bright light it doesn’t really have that same ‘for God’s sake don’t look round!’ factor so beloved by the red-tops.

Anthony Hardy, Martha Beck, Catherine Birnie, David Copeland, H H Holmes, Karla Homolka, Ted Kaczynski, Richard Chase, Peter Kurten, Kenneth Bianchi, Levi Bellfield, Albert Fish and Jeffrey Dahmer were all born in May, a month associated with warming sun and blooming flowers, not infanticide, dismemberment and cannibalism.

I tried searching on Google Scholar, but could not find any papers on the subject. So, I have the following questions:

  1. Is it true that there are more serial killers born in November than in any other month?
  2. If that's true, is there any explanation?
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    Note that the conclusion of your second source, if you read past the headline, is that there were twice as many serial killers born in May than in November. Also note that the definition of a serial killer is not etched in stone so the statistics related to birth month can be altered to fit other conclusions. Also note that many serial killers have not been identified so that the data only covers known killers. Maybe there is a reason that serial killers born in November are more prone to capture.
    – Barry
    Commented Sep 30, 2021 at 1:06
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    Well, one month has to have the most. And listing a few notorious examples that happen to share their month of birth isn't convincing; that just leads to the 27 Club.
    – SQB
    Commented Sep 30, 2021 at 7:54
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    The sample size of serial killers seems to be miniscule. Random statistical fluke would be a perfectly valid explanation. Commented Sep 30, 2021 at 8:44
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    FWIW, based on the Wikipedia list of serial killers and the date of births known in Wikipedia, it is not true. I was able to automatically extract 79 DOBs from the articles about serial killers and most of them are in February and May. As Sebastian already pointed out: With such a small sample size, large variations must be expected. en.wikipedia.org/wiki/… Commented Sep 30, 2021 at 10:21
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    This might be a "theory answer", but I did a quick simulation. If you generate 100 randomly selected months, then about 4.3% of the time, one of them will occur at least 17 times. So this just barely meets the usual p<0.05 threshold of statistical significance to reject the null hypothesis - i.e. we can't completely dismiss it as "statistical fluke". Commented Sep 30, 2021 at 13:47

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