Behavioral and Brain Sciences

Authors' Response
Jonathan J. Koehler (1996). The base rate fallacy reconsidered: Descriptive, normative, and methodological challenges. BBS 19:1–53.

A farewell to normative null hypothesis testing in base rate research

Jonathan J. Koehler a1
a1 Graduate School of Business and Law School, University of Texas at Austin, Austin, TX 78712 [email protected] edu


I agree with Gibbs that the message of the base rate literature reads differently depending on which null hypothesis is used to frame the issue. But I argue that the normative null hypothesis, H0: “People use base rates in a Bayesian manner,” is no longer appropriate. I also challenge Adler's distinction between unused and ignored base rates, and criticize Goodie's reluctance to shift research attention to the field. Macchi's arguments about textual ambiguities in traditional base rate problems suggest that empirical testing is needed to tease apart the effects of problem clarification and problem framing. Macdonald's, Fletcher's and Snow's skepticism about the value of Bayesian methods in real world judgment tasks is treated as a challenge for the next generation of empirical base rate studies.