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Why a treatment can win in every group and still lose overall: Simpson's paradox Treatment B beats Treatment A overall, yet A wins for small stones and for large stones. That is Simpson's paradox, and it is real data from a kidney-stone… Maths4 min read3 Nov Why random bounces pile up into a bell curve: the Galton board Every ball in a Galton board makes the same blind choice at each peg: left or right, a coin flip. Yet drop enough of them and the pile always grows into the… Maths4 min read13 Oct Why the most common word is twice as common as the next: Zipf's law Sort every word in a book from most to least common and a pattern appears: the top word is about twice as common as the second, three times as common as the… Language5 min read10 Oct Why washing hands saved mothers in 1847: Semmelweis and the two wards In 1846, mothers in one Vienna maternity ward died at four times the rate of mothers in the ward next door. The doctors' ward was losing 11.4% of its patients… History3 min read7 Oct Why 1 leads far more often than 9: Benford's law of first digits Look only at the first digit of any long list of real-world numbers, such as river areas, populations or the figures in a company's accounts. You'd expect each… Maths3 min read7 Oct Why 23 people are enough for two to share a birthday Put 23 people in a room and there's a better-than-even chance that two of them share a birthday. That sounds wrong, because 23 is tiny next to 365. The catch… Maths4 min read29 Sep Why the most common words are the shortest: Zipf's two laws of language Count the words in almost any long text and a strange pattern appears: the most common word turns up about twice as often as the second, three times as often… Language5 min read26 Sep