G. Gigerenzer et U. Hoffrage, Overcoming difficulties in Bayesian reasoning: A reply to Lewis and Keren (1999) and Mellers and McGraw (1999), PSYCHOL REV, 106(2), 1999, pp. 425-430
Bayesian reasoning can be improved by representing information in frequency
formats rather than in probabilities. This thesis opens up applications in
medicine, law, statistics education, and other fields. The beneficial effe
ct is no longer in dispute, but rather its cause and its boundary condition
s. C. Lewis and G. Keren (1999) argued that the effect of frequency formats
is due to "joint statements" rather than to "frequency statements." Howeve
r, they overlooked the fact that our thesis is about frequency formats, nor
just any kind of frequency statements. We show that joint statements alone
cannot account for the effect. B. A. Mellers and A. P. McGraw (1999) propo
sed a boundary condition under which the beneficial effect is reduced. In a
reanalysis of our original data, we found this reduction for the problem t
hey used but not for any other problem. We conclude by summarizing results
indicating that teaching frequency representations fosters insight into Bay
esian reasoning.