I know plenty of economists who are fond of Guinness, but not many who realise just how important the beer has been to the profession. The man who laid the foundations for the global success of Guinness also produced one of the most important tools in economics – and a tool that is widely mishandled today.
Faced with an apparent pattern in any data, a key question is always: “Does this pattern represent something real, or is it just chance?” The simplest example: if I measure the heights of five men and five women and discover that the men tend to be taller than the women, I might be on to something, or I might just have some tall men and some short women in my sample. Based on this small sample, how confident should I be that men are in general taller than women?
The statistical apparatus to check this is a test called Student’s t-test. Student was the pseudonym of William Sealy Gosset, an amiable, rucksack-wearing chemist who – beginning in 1899 – worked all his adult life for Guinness and eventually rose to the rank of head brewer. So nervous was the company about commercial confidentiality that Gosset published surreptitiously under his pseudonym.
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