st: sample size calculation (Help)

 From "Yan Cheng" To statalist@hsphsun2.harvard.edu Subject st: sample size calculation (Help) Date Thu, 15 Mar 2007 11:45:07 +0800

```Hello, everyone:
I want to get a sample size of two-sample comparison of
proportions. It is a cross-sectional survey between two sites and I
would analyze the differences of some proportions between two site. In
order to control the might confunding caused by gender and age, the
sample was divided into 6 strata by gender (male or female ) and age
(lower, middle, higher) and in each stratum the sample size is equal,
Thus, it is easy to compare the difference between two sites without
considering the difference caused by gender and age in the sample,
that is, the total of sample size would be 6*(sample in each stratum).
Then, how do I estimate the sample size?

Many thanks for your consideration in advance!

Best,

Cheng Yan
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