If statistics aren't your cup of tea, try Doctor Fisher's taste test And so now our days are punctuated, not only by Clipper's Earl Grey made just the way I like it, but also with the act of stopping to make it in the first place. Hardly some Japanese ritual. But still: leave desk. Boil water. Pour. Wait. Remove bag with spoon. Milk. It takes a while for me to explain to Adam what I meant by that reference to Sir Ronald Fisher. Adam is a mathematical modeller: they count as statisticians, and are allowed to dine with us (and drink our tea), but they're less well-up on one of the most significant experiments of the 20th century. In the Twenties, Ronald Fisher worked on agricultural research at Rothamsted Experimental Station. On the side of his day job, he developed a theory for the design and analysis of experiments which has dominated empirical research since. Every time you see a news item which reports a "significant link between [disease] and [food/behaviour]," or that "scientists believe these results cannot be due to chance," the language and conclusion are down to Fisher. I (and millions of statisticians) fundamentally disagree with Fisher's method for testing hypotheses, but the mathematical framework he invented is the origin of the modern scientific approach. Look him up on Google: when journalists describe such-and-such a politician as "clever," I think of Fisher, and snigger, I'm afraid, with disdain. Be that as it may. Fisher was also a tea-drinker, and one afternoon found himself in the common room at Rothamsted with another scientist, Dr Muriel Bristol. He offered her a cup of tea which he had just made. There is an account of what followed, recounted in the biography of Fisher by another great statistician, George Box, but I prefer to dream a little about these characters. I've never watched Downton Abbey, but I imagine something like this: "Oh no," said Muriel, suppressing a faint shudder. I couldn't drink that. Disgusting. "Eh?" said Ronald, peering at the cup of brown liquid at the end of his outstretched arm. What's wrong with it? It's just tea. Muriel laughed, to cover the depth of her revulsion. You put the tea in before the milk. Scalding the china. I dislike the taste. Seeing Ronald's confusion, she became firmer: "Please. Take it away. We do know that Fisher then responded: "Nonsense. Surely it makes no difference. But Bristol stuck to her guns, and so Fisher decided to test her. Eight cups of tea would be prepared, four of which were made Bristol fashion (milk first), the other four Fisher-style (tea first). Dr Bristol would know those facts, then taste each cup, and declare whether or not the milk had entered first. Her score would determine the validity of her hypothesis that the milk/tea order matters sufficiently for her to be able to taste the difference. The details of this experiment - or, rather, the details of how to interpret its results - have provided philosophers of science with meat for discussion ever since. If you're thinking "how trivial," you're wrong (and not invited to dine with statisticians). Even Fisher developed more than one solution, although if cats can look up from their un-tannined saucers of milk for a moment, and gaze upon kings, then let me declare that I believe his reasoning to be faulty. I tell Adam this. He looks at me. "What happened?" he asks. I start to explain the problems with Fisher's theory. "No," he interrupts. How did Muriel do? Jane: "She got all eight right. The order does matter. And then she says to me: "That's why I hate it when you make the tea."