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st: Power calculation


From   K C Wong <kcwong5@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Power calculation
Date   Mon, 20 Aug 2012 14:52:23 +1200

Hi everyone.

I'd like to ask how do I calculate the power given I have this information?

1)For the N of cases it is 1200 cases in total. (Asian 200 and Europen
1000) and for the denominator, the N is 1000000.

2) Using data from the cancer registry and census population based
data for the denominators, we will test the hypotheses of blah blah
blah among Asian compared to European. Following standard study design
for comparison of incidence rates across groups, we will use Poisson
regression. In these analyses, we will be able to control for variabe
A, B and C. We estimate that we have adequate power to test our
hypothesis, since with an N of XXXX cases (XXX Asian and XXXX
European) we have XX% power (alpha = 0.05) to detect a relative risk
of at least 2.

My apology for any unclarity.
Your input is greatly appreciated.
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