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Base Rates

  1. Jan H. Kamphuis

Published Online: 30 JAN 2010

DOI: 10.1002/9780470479216.corpsy0109

Corsini Encyclopedia of Psychology

Corsini Encyclopedia of Psychology

How to Cite

Kamphuis, J. H. 2010. Base Rates. Corsini Encyclopedia of Psychology. 1–2.

Author Information

  1. University of Amsterdam, The Netherlands

Publication History

  1. Published Online: 30 JAN 2010


Base rates refer to the relative frequencies with which certain states or conditions occur in a population. The concept denotes the same as prevalence, a term often used by epidemiologists. A base rate is defined for and restricted to a specified population. In other words, a base rate is the a priori chance or prior odds that a member of a specified population will have a certain characteristic, assuming that we know nothing else about this person other than that he or she is a member of the population we are examining (Kamphuis & Finn, 2002). For example, the base rate of suicide in the general population is less than 1%, whereas the base rate of suicide for a more restricted population, for example, among patients with borderline personality disorder, may be as high as 10%.