[R] significance in difference of proportions

Jonathan Baron baron at psych.upenn.edu
Thu Nov 27 18:09:04 CET 2003

On 11/27/03 17:04, Arne.Muller at aventis.com wrote:
>I'm looking for some guidance with the following problem:
>I've 2 samples A (111 items) and B (10 items) drawn from the same unknown
>population. Witihn A I find 9 "positives" and in B 0 positives. I'd like to
>know if the 2 samples A and B are different, ie is there a way to find out
>whether the number of "positives" is significantly different in A and B?
>I'm currently using prop.test, but unfortunately some of my data contains
>less than 5 items in a group (like in the example above), and the test
>statistics may not hold:

fisher.test in the ctest package, which loads automatically.

Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page:            http://www.sas.upenn.edu/~baron

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