The only relevant test of the validity of a hypothesis is comparison of prediction with experience. is a quote of American economist and statistician Milton Friedman (1912 - 2006). The quote can be found in the chapter "The methodology of positive economics" written by Dr. Friedman as an original article in his 1953 book "Essays in Positive Economics" containing a collection of his earlier articles.
A cartoon to teach about the need to think carefully about the assumptions underlying a statistical model (also uses the idea that you can multiply chances for independent events to find the chance that they all occur). Drawn by British cartoonist John Landers based on an idea from Dennis earl. Free to use in the classroom and on course websites.