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re: st: sampsi and percentages

From   "Ariel Linden, DrPH" <[email protected]>
To   <[email protected]>
Subject   re: st: sampsi and percentages
Date   Tue, 30 Aug 2011 08:51:05 -0400


I may be mistaken here, but it seems you have two proportions (if it's
bounded between 0,1 then you have a numerator and a denominator for each

If that is truly the case, you can use sampsi for proportions:

. sampsi 0.25 0.4

Estimated sample size for two-sample comparison of proportions

Test Ho: p1 = p2, where p1 is the proportion in population 1
                    and p2 is the proportion in population 2

         alpha =   0.0500  (two-sided)
         power =   0.9000
            p1 =   0.2500
            p2 =   0.4000
         n2/n1 =   1.00

Estimated required sample sizes:

            n1 =      216
            n2 =      216

I hope this helps


Date: Mon, 29 Aug 2011 11:40:33 -0700 (PDT)
From: Ricardo Ovaldia <[email protected]>
Subject: st: sampsi and percentages

I need to compute sample size and power for a study comparing two group on a
measurement bounded by (0,1), (a measure of intensity).
I was thinking about using -sampsi- to power on the difference of means.
However, this seems strange to me, is there another way to power such
Thank you,

Ricardo Ovaldia, MS
Oklahoma City, OK


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