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st: Control groups

From   <>
To   <>
Subject   st: Control groups
Date   Fri, 9 May 2008 23:52:13 +0200

Dear Statalisters,

Say I have a population of 500 000. I would like to treat this
population with some sort of communication, and to be able to measure
the effect of this treatment I have the opportunity to draw a control
group. Based on earlier experiences the effects between the treated and
the controlgroup could be as small as 0.5%.

I want to be able to detect such a small effects, and I am wondering how
large my control groups ideally would be to track these changes, say at
an alpha level of 0.05.

I have tried to use the fpower (findit fpower) and the simpower (findit
simpower) to determine optimal control group sizes. I am curious whether
there are other alternatives in Stata?

Thanks! And have a nice weekend.

Best wishes,

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