ABSTRACT
Numerous studies have investigated the use of base rates in probabilistic reasoning. Early results of these studies suggested that people generally ignore or neglect base rate probabilities. A famous problem initially proposed by Kahneman and Tversky (1973, pp. 237-238) was the following:
A panel of psychologists have interviewed and administered personality tests to 30 engineers and 70 lawyers, all successful in their respective fields. On the basis of this information, thumbnail descriptions of the 30 engineers and 70 lawyers have been written. You will find on your forms a description, chosen at random from the 100 available descriptions. For each description, please indicate your probability that the person described is an engineer, on a scale from 0 to 100.
