--- "Lin, Chung-Tung" <[email protected]>
wrote:
> you may want to look at the sampsi command for
> details.
Thank you Jordan Lin, but -sampsi- requires that you
specify means and SD, which I do not have and is the
reason that I asked the question.
Regards,
Ricardo.
>
>
> -----Original Message-----
> From: Ricardo Ovaldia [mailto:[email protected]]
> Sent: Wednesday, September 29, 2004 2:04 PM
> To: [email protected]
> Subject: st: sample size calculation
>
>
> Dear all,
>
> In an article that I am reading the authors write:
>
> "it was decided a priori to include a minimum
> quantity
> of mother, which could allow the statistical power
> (alpha=0.05, beta=0.80) for assessing
> differences of 10% in nicotine concentration by
> group
> with an expected standard deviation of 15 ng/mg.
> These
> criteria led to the analysis of 150 mothers (50 for
> each of the 3 groups)"
>
> They claim that they did this and all analysis using
> Stata 5.0. They do not provide group means or any
> descriptive statistics on which the sample size was
> computed.
>
> Can someone please tell me how this could have been
> done. And is there a program to do this in Stata?
>
> Thank you in advance,
> Ricardo
>
>
>
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=====
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
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