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Re: st: RRR with CI from logit model


From   Michael Ingre <Michael.Ingre@ipm.ki.se>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RRR with CI from logit model
Date   Mon, 1 Nov 2004 15:54:01 +0100

A follow up on statistical power.

I have calculated a few RRRs and an interesting pattern is emerging. Extreme comparisons give insignificant p-values but others don't.

RRR for 9.5 vs 1, p=.669
RRR for 9.5 vs 9, p=.030
RRR for 2 vs 1, p=.049

Predicted absolute probabilities are: 9.5=.33 , 9=.14, 2=.000020 & 1=.000015

What is going on here? Am I doing something wrong? I appreciate any suggestion because this makes no sense to me.


Michael


nlcom exp(81 * squared + 9 * linear + constant) /              ///
         (1 + exp(81 * squared + 9 * linear + constant)) /    ///
      exp(4 * squared + 2 * linear + constant) /            ///
	     (1 + exp(4 * squared + 2 * linear + constant))



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