Years ago I signed up for a feed from www.quora.com and read the traffic there far more than I should. Quora is a stream of inane questions, interspersed with kids expecting adult strangers to do their homework for them but it is 'mostly harmless'. Occasionally something interesting pops up:
That was from Jérôme Cukier's answer to the question "What are some surprising or non trivial statistical facts about Facebook users". I'm one of the last holdouts against the Empire of the Zuckerclones but I thought one of the terms of service was that a) you have to use your own name and b) you had to be over 18. That's fatuous because unenforceable. Facebook also asks for your birthday, ostensibly so that their robots can send you an e-cake with pixie candles on the day and make you think that somebody cares. Well it seems that, in the rush to get registered, people put down any old date when asked with notably preference for the 1st of any month or 01/01 02/02 etc. dates. Particular /peculiar chosen dates include 4th of July and Valentine's Day. You can maybe see the shadow of the [real] September births are up trend. You should always take the results from questionnaires with a skeptical pinch of salt.
Designers of census forms please note. One of the anomalies thrown up was the existence of a number of teenagers who had endured multiple pregnancies. The most likely explanation was that ages like 76 and 79 had been tallied up as 16 and 19. Most of the time it doesn't matter much because that's what standard error is for. All those blips up and cancelled out by blips down and the Census finishes up correct with an allowable +/- error of estimate. Sometimes the errors are from laziness and ineptitude of the enumerators or the punters. Then again, sometimes it's because some people are a little hazy about the facts of life. Recent surveys have found 5 women in every 1000 who have been pregnant but have never had sex. The same source reported a few virgin fathers but that smacks of cuckoldry. Similar transcriptional errors recorded in The Blob