Following up my last entry about studies that were not reproducible, I found this nice entry about the Tea Tasting Lady.
Now comes the story of the lady that was peculiar about her tea. She liked her tea with milk, but you had to put the milk first and then the tea, or else she said, the tea would be ruined. Your reaction (as mine was) is that it is impossible to tell the difference. But how can you prove it?
Well, if you give the lady one cup of tea with milk added first, she has 50% change of getting it right. If you give her two cups of tea (with milk or tea added first randomly), she now only has 25% chance of getting it right. If you were to give her 5 randomly filled cups of tea with milk, her chance of getting them all right is around 3% (we usually say that a result is significant if the chances of getting it randomly are <5%).
Well, this story is real, and she was really able to tell the difference
Full article
http://blinkingcaret.wordpress.com/2012/10/02/tdd-bdd-add-every-other-method-that-promises-software-quality-here-and-the-tea-tasting-lady/