Last week, the Freakonomics blog in the NYT reported that the Israeli lottery had drawn the same six numbers twice in a month. The seventh "bonus ball" was different, but still: quite a coincidence, right? Cue the quote from an expert to explain just how remarkable this is:
Yitzhak Melechson, a statistics professor at the University of Tel Aviv, said that “the incident of six numbers repeating themselves within a month is an event of once in 10,000 years.”
Hmm, not so much. As Xi'an pointed out, there's actually about an 8% 8 in 1000 chance of this having occurred in the two years the Israeli lottery has been run under these rules. And then if you consider all the lotteries around the world, as we did when the Bulgarian lottery had back-to-back identical drawings just over a year ago, then this isn't looking so surprising after all. It's likely that Yitzhak Melechson was misquoted, but still, as Gelman says, it's surprising the guys at Freakonomics missed this one.
Update: Corrected estimate of the probability of coincidence. Apologies for the error, which was mine, not Xi'an's.
Freakonomics blog: Very Long Odds in the Israeli Lottery