Lady tasting tea

In the design of experiments in statistics, the lady tasting tea is a famous randomized experiment devised by Ronald A. Fisher and reported in his book Statistical methods for research workers (1925). The lady in question was Dr. Muriel Bristol, and the test used was Fisher's exact test.

In popular science, David Salsburg published a book entitled The Lady Tasting Tea, which describes Fisher's experiment and ideas on randomization.

The lady in question claimed to be able to tell whether the tea or the milk was added first to a cup. Fisher proposed to give her eight cups, four of each variety, in random order. One could then ask what the probability was for her getting the number she got correct, but just by chance.

Salsburg reports that a colleague of Fisher, H. Fairfield Smith revealed that in the test, the woman got all eight cups correct. The chance of someone who just guesses getting all correct, assuming she guesses that four had the tea put in first and four the milk, would be only 1 in 70 (the combinations of 8 taken 4 at a time).

Deb Basu wrote that "the famous case of the 'lady tasting tea'" was "one of the two supporting pillars . . . of the randomization analysis of experimental data".

See also

• Permutation test
• Random assignment
• Randomization test

References

• Basu, D. (1980a). "Randomization Analysis of Experimental Data: The Fisher Randomization Test". Journal of the American Statistical Association 75 (371): 575–582. doi:10.2307/2287648. JSTOR 2287648. 

• Basu, D. (1980b). "The Fisher Randomization Test", reprinted with a new preface in Statistical Information and Likelihood : A Collection of Critical Essays by Dr. D. Basu ; J.K. Ghosh, editor. Springer 1988.

• Kempthorne, Oscar. "Intervention experiments, randomization and inference". In Malay Ghosh and Pramod K. Pathak. Current Issues in Statistical Inference—Essays in Honor of. Hayward, CA.: IMS. pp. 13–31. doi:10.1214/lnms/1215458836. http://projecteuclid.org/euclid.lnms/1215458836. 

• Salsburg, D. (2002) The Lady Tasting Tea: How Statistics Revolutionized Science in the Twentieth Century, W.H. Freeman / Owl Book. ISBN 0-8050-7134-2

External links

• "Lady Tasting Tea", by Lt. Col. Rod Sturdivant, Ph.D., U.S. Military Academy, Dept. of Mathematical Sciences. Adapted from: Nolan, D., Speed, T. (2000) Stat Labs: Mathematical statistics through applications, Springer-Verlag. ISBN 0387989749 (Chapter 6)