There is a thread on alt.folklore.urban that begins with the classic OR story of looking for places to increase shielding on planes in WWII: analysis of where holes were on planes was somewhat skewed by being limited to those that returned. This then goes on to other analyses: first a researcher concludes, based on prison interviews, that people of low intelligence commit crimes. This is updated to conclude criminals of low intelligence go to prison. Further updates suggest people (not necessarily criminals) of low intelligence go to prison. Interesting thread!