The base rate fallacy, also called base rate neglect, is a logical fallacy that occurs when irrelevant information is used to make a probability judgment, especially when empiricalstatistics about the probability are available (called the "base rate" or "prior probability").
In some experiments, students were asked to estimate the Grade Point Averages of hypothetical students. When given relevant statistics about GPA distribution, students tended to ignore them if given descriptive information about the particular student, even if the new information did not seem to have anything to do with school performance.
This finding has been used to argue that interviews are an unnecessary part of the college admissions process because empirical evidence shows that interviewers are unable to pick successful candidates better than basic statistics. Similarly, economists argue that stock market brokers commit this mistake because market performance and the performance of any individual stock are indistinguishable from chance movement, and professionally-chosen portfolios do no better than those composed of stocks picked at random.
Richard Nisbett has argued that some attributional biases like the fundamental attribution error are instances of the base rate fallacy: people underutilize "consensus information" (the "base rate") about how others behaved in similar situations and instead prefer simpler dispositional attributions.
Bar-Hillel, M. (1980). The base-rate fallacy in probability judgments. Acta Psychologica, 44, 211-233.
Kahneman, D., & Tversky, A. (1973). On the psychology of prediction. Psychological Review, 80, 237-251. (summary here (http://faculty.babson.edu/krollag/org_site/soc_psych/kan_tver_pred.html))
Nisbett, R. E., Borgida, E., Crandall, R., & Reed, H. (1976). Popular induction: Information is not always informative. In J. S. Carroll & J. W. Payne (Eds.), Cognition and social behavior, 2, 227-236.
External links
Psychology of Intelligence Analysis: Base Rate Fallacy (http://www.cia.gov/csi/books/19104/art15.html#ft145)
The baseratefallacy, also called baserate neglect, is a logical fallacy that occurs when irrelevant information is used to make a probability judgment, especially when empirical statistics about the probability are available (called the "baserate" or "prior probability").
Richard Nisbett has argued that some attributional biases like the fundamental attribution error are instances of the baseratefallacy: people underutilize "consensus information" (the "baserate") about how others behaved in similar situations and instead prefer simpler dispositional attributions.
Bar-Hillel, M. The base-rate fallacy in probability judgments.
A fallacy is a component of an argument that is demonstrably flawed in its logic or form, thus rendering the argument invalid (except in the case of begging the question) in whole.
Fallacy of Accident (also called destroying the exception or a dicto simpliciter ad dictum secundum quid) meaning to argue erroneously from a general rule to a particular case, without proper regard to particular conditions that vitiate the application of the general rule; e.g.
Fallacy of Many Questions (Plurium Interrogationum), wherein several questions are improperly grouped in the form of one, and a direct categorical answer is demanded, e.g.
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