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This forum is about wrong numbers in science, politics and the media. It respects good science and good English.

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Is this the birthday fallacy?

The silly season is in full swing and a possible birthday fallacy makes it's eagerly awaited appearance, this time in the Telegraph. You can find it

The article itself is very poorly written, confusing birth dates, and dates of conception. But from the content we can see the Trojan number was 800,000 and that of children conceived in the first quarter of the year 8.9% had learning difficulties compared with 7.6% of those conceived between July and September. Usually with these things they quote months, but the grouping into seasons suggests some statistical chicanery has been employed, but I think we could guess that already.

It's all down to lack of vitamin D apparently.

Like John's classic example this one hails from Scotland.

The reason I ask is this the birthday fallacy is that the numbers are large, and therefore more likely to be significant. Obviously this all pre-supposes accurate diagnosis etc. A link to the full data would yield some answers.

Re: Is this the birthday fallacy?

What causes my BS meter to fly is the use of First Quarter vs "July through September". How many different ways can we group months to make the same approximation.

I think you are correct to classify it with Birth Month Fallacy. It is just worse than the birth month fallacy. It is the Birth Quarter fallacy.