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Cereal correlation

- January 29, 2009

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bq. 56% of women who consumed the most calories before conception gave birth to boys, compared with 45% of those who consumed the least. Of 132 individual foods tracked, breakfast cereal was the most significantly linked with baby boys.

That’s from a study by researchers at Exeter and Oxford, as per Melinda Beck’s write-up in the Wall Street Journal.

This made me wonder. After all, my brothers and I turned out to be, well, boys, and my mother never ever ate breakfast cereal. However, as a social scientist I recognize that correlational results admit of exceptions.

They also, as Beck notes, occasion doubt. One of the first things one is supposed to learn about “statistical significance” is that some results that appear to be real, aren’t. If you’re operating at the .05 significance level, then in the long run somewhere around 5% of the relationships that you accept as non-random should really be random. Those are “Type 1” errors — or are they “Type 2” errors? I could never keep those straight. (Andrew, though not not a frequentist, presumably can straighten me out here.) Anyway, these breakfast cereal results apparently have produced a minor kerfuffle among epidemiologists and statisticians, which you can read about in the Beck article. If nothing else, this episode provides a nice example for those who are teaching intro methods courses, and it also gives “Monkey Cage” readers an opportunity to admire the excellent pun I devised for the headline of this item. (Please hold your applause.)