Lady tasting tea
Encyclopedia
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 combination
s 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".
Design of experiments
In general usage, design of experiments or experimental design is the design of any information-gathering exercises where variation is present, whether under the full control of the experimenter or not. However, in statistics, these terms are usually used for controlled experiments...
in statistics
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
, the lady tasting tea is a famous randomized experiment
Randomized experiment
In science, randomized experiments are the experiments that allow the greatest reliability and validity of statistical estimates of treatment effects...
devised by Ronald A. Fisher and reported in his book Statistical methods for research workers
Statistical Methods for Research Workers
Statistical Methods for Research Workers is a classic 1925 book on statistics by the statistician R.A. Fisher. It is considered by some to be one of the 20th century's most influential books on statistical methods. According to ,...
(1925). The lady in question was Dr. Muriel Bristol
Muriel Bristol
B. Muriel Bristol-Roach, Ph.D., was a scientist working in the field of alga biology who worked at the Rothamsted Experimental Station in 1919. In addition to her scientific work, she is notable for being the woman whose claim to be able to tell whether the milk or the tea was poured into a cup...
, and the test used was Fisher's exact test
Fisher's exact test
Fisher's exact test is a statistical significance test used in the analysis of contingency tables where sample sizes are small. It is named after its inventor, R. A...
.
In popular science
Popular science
Popular science, sometimes called literature of science, is interpretation of science intended for a general audience. While science journalism focuses on recent scientific developments, popular science is broad-ranging, often written by scientists as well as journalists, and is presented in many...
, David Salsburg
David Salsburg
David S. Salsburg gained fame as the author of The Lady Tasting Tea, subtitled How Statistics Revolutionized Science in the Twentieth Century...
published a book entitled The Lady Tasting Tea
The Lady Tasting Tea
The Lady Tasting Tea: How Statistics Revolutionized Science in the Twentieth Century is a book by David Salsburg about the history of modern statistics and the role it played in the development of science and industry....
, which describes Fisher's experiment and ideas on randomization
Randomization
Randomization is the process of making something random; this means:* Generating a random permutation of a sequence .* Selecting a random sample of a population ....
.
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 combination
Combination
In mathematics a combination is a way of selecting several things out of a larger group, where order does not matter. In smaller cases it is possible to count the number of combinations...
s 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".
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)