In the design of experiments in statistics, the lady sipping tea is a randomized experiment reported by Ronald Fisher in his 1935 book The Design of Experiments.
One day, Ronald Aylmer Fisher (the inventor of experimental design) witnessed a scene in which a lady was outraged:
She had been served tea with milk first!
Fisher, amused, doubted, however, that the order in which the tea and milk were added would affect the taste of the drink. The lady said she could taste a difference.
Fisher challenged her. He devised a test that is still known as Fisher's Exact Test. Simply compare 4 cups for each configuration. If all 8 cups are recognized, then the difference is statistically proven.
La Lady had no difficulty in recognizing the order in which many more cups were prepared than was necessary to prove her assertion. In his book, Fisher's description runs to less than 10 pages, and is distinguished by its simplicity and completeness in terms of terminology, calculations and experimental design.
Even if the Y is not measurable, it's easy to provide statistical proof of a difference. Six Sigma can be as simple as that! To find out more about experimental design, you can follow our training.
