Belief in the Law of Small Numbers
-- A. Tversky and D. Kanheman. Psychological Bulletin, 1971, Vol. 76, No. 2. 105-110.
People have erroneous intuitions about the laws of chance. In particular, they regard a sample randomly drawn from a population as highly representative, that is, similar to the population in all essential characteristics. The prevalence of the belief and its unfortunate consequences for psychological research are illustrated by the responses of professional psychologists to a questionnaire concerning research decisions.