Talk:Base rate fallacy

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For instance, appealing to vivid examples should not be taken knowledge of prior probabilities.

I don't understand what this statement means? CSTAR 19:44, 17 Jun 2004 (UTC)

Yea, that makes no sense. I'll fix it in a minute. --Taak 21:36, 17 Jun 2004 (UTC)

I thought that base rate neglect involved ignoring priors in a Bayesian context. For example, if a medical test with a 5% false positive rate is applied to a population whose background incidence of the disease is, say, 1%, the great majority test results will be faulty: they will indicate disease where there is none. It's not that the medical test is irrelevant though: rather its significance can be overweighed.

[edit] Fallacies in example

"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 descriptive 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."

This is fallacious in itself:

Students ignore statistics in favour of descriptive information.
College interviews give a form of descriptive information.
Therefore, college interviewers will ignore statistics in favour of descriptive information.

The descriptive information given to students in the experiment were irrelevant.
College interviews give a form of descriptive information.
Therefore, college interviews are irrelevant when considering suitability of an academic candidate.

The first fallacy assumes that students and college interviewers possess the same lack of skill in judging relevance of information.

The second fallacy assumes:
A. Statistics are always relevant, and descriptive information is always irrelevant.
AND/OR
B. Statistics are a better judge of suitability for academic placement than descriptive information.
-- Sasuke Sarutobi 21:26, 12 December 2006 (UTC)