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st: power calculations


From   "Airey, David C" <david.airey@Vanderbilt.Edu>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: power calculations
Date   Thu, 4 Feb 2010 21:30:32 -0600

.

There was an article in the Stata Journal Vol 3 issue 1 on power analysis in case-control situation, though it focused on geneXgene and geneXenvironment interactions. Otherwise you must simulate accounting for allele frequency, penetrance, etc., or look for other tools (e.g., http://pngu.mgh.harvard.edu/~purcell/gpc/; http://dceg.cancer.gov/bb/tools/pga).

-Dave



> Dear listers,
> 
> I am doing two diffent studies, using Stata 11. The first is a cross-sectional study (n=42,298), the second a case-control study (n1=4,851/n2=4,851).
> 
> I am looking at a specific genotype with a frequency of 0.6% in both studies (variable of interest), the endpoint is IHD (Ischemic Heart Disease).  I have some difficulties with the power calculations. I want to estimate the minimal value (odds ratio) that can be detected with 80% power for both studies...But what is the right way to do this in Stata? As far as I can tell the sampsi command can+determine power or sample size - not minimal detectable effect size?
> 
> 
> Best regards,
> 
> 
> Louise Stig Hornstrup, MD, PhD-student
> Dept. Clin. Biochem., 4111.
> Rigshospitalet, Copenhagen
> Denmark

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