Lady tasting tea
Lady tasting tea is the name of a famous randomized experiment designed by Ronald Fisher in 1935. The experiment is the original exposition of Fisher's notion of a null hypothesis. Fisher's description is less than ten pages long and is notable for its simplicity and completeness regarding terminology, calculations and design of the experiment. The example is loosely based on an event in Fisher's life. The lady in question was Muriel Bristol, and the test used was Fisher's exact test.