What's the difference between a physicist, a mathematician, and a statistician?
The physicist calculates until he gets a correct result and concludes that he has proven a fact.
The mathematician calculates until he gets a wrong result and concludes that he has proven the contrary of a fact.
The statistician calculates until he gets a correct result about an obviously wrong proposition and concludes NOTHING, because the explanation is the task of the scientist who consulted the statistician.
*Thanks to Robert Hacker from Austria for this one. I hope I have not done damage to the underlying humor in the translation.