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AW: st: power calculation graphs
From
"Martin Weiss" <[email protected]>
To
<[email protected]>
Subject
AW: st: power calculation graphs
Date
Fri, 20 Aug 2010 12:07:46 +0200
<>
Re -postfile-, also see
http://www.michaelnormanmitchell.com/stow/month/march-2010
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Neil Shephard
Gesendet: Freitag, 20. August 2010 12:04
An: [email protected]
Betreff: Re: st: power calculation graphs
On Fri, Aug 20, 2010 at 8:54 AM, Nikolaos Pandis <[email protected]> wrote:
> Hi to all.
>
> I was wondering if someone would be able to help me draw the following
sample calculation graphs with Stata:
>
> 1. Two arm parallel trial, outcome binary.
>
> A power (y-axis) sample size (x-axis) calculation graph for various
failure proportions between trial arms. For example, p1=0.80 and p2=0.85, or
p1=0.80 p=0.90 or p1=0.80 p=0.95
>
>
> 2. Two arm parallel trial, outcome continuous.
>
> A power (y-axis) sample (x-axis) calculation graph for various failure
proportions between trial arms. For example, m1= 100 and m2= 120 with equal
sd1=sd2=10. It would be great if I could vary m1, m2, sd (always sd1=sd2)
>
You can do both of these using the -sampsi- command and could have
found this yourself by typing -search sample size- into Stata.
If you want to do the analysis for a range of values then you should
consider putting each call within a series of nested -forval- loops
and write the results to a file using -postfile- which you can then
read into Stata and draw the graphs you want.
I'll leave the actual coding of this as an exercise for you to work on ;-)
Neil
--
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necessary to avoid starvation and to keep out of prison, but anything
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ways..." - Bertrand Russell
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