"To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of." - Sir Ronald A Fisher
"The plural of anecdote is not data." - Roger Brinner
"The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data." - John Tukey