st: Sample size calculations

[Amal Khanolkar <Amal.Khanolkar@ki.se>]

Hi,

I plan to run a set of multivariate linear regressions models which will help analyze ethnic differences in my outcome of interest. 

regress Y i.ethnicity age i.education height bmi bloodpressure

I have 14 different ethnic groups.

As some of my ethnic groups are fairly small I would like to calculate the sample size needed for each of the fourteen ethnic groups. I have a rough idea of the expected effect or parameter p in each ethnic group.

I've only calculated sample sizes for a two group comparison using the sampsi command in Stata.

Does anyone know how I could go about testing expected sample sizes for several categories of the exposure variable?

I would set other parameters needed to calculate sample size as follows: alpha=0.05, power (0.90), expected effect for most ethnic groups varies between -2.85 to -7.65

Thanks & regards

Amal




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