The Importance of a Cup of Tea

Could you tell the difference between the taste of a cup of tea where the milk was poured first, and one where the milk was poured last?

In 1919, an English lady, Dr. Muriel Bristol, declared that she could. A statistician named Ronald Fisher set out not only to disprove her claim, but to do so in as mathematically sound a manner as possible.

As it happens, Dr. Bristol defended her discriminating palate.

By the eighth cup Fisher was goggle-eyed behind his spectacles. Bristol had gotten every single one correct.

Trying to understand the significance of this result inspired Fisher to develop novel rigorous statistical methods for testing hypotheses.

Fisher published the fruit of his research in two seminal books, Statistical Methods for Research Workers and The Design of Experiments. The latter introduced several fundamental ideas, including the null hypothesis and statistical significance, that scientists worldwide still use today. And the first example Fisher used in his book, to set the tone for everything that followed, was Muriel Bristol’s tea test.

Via the Irish Times and the Science History Institute.