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Re: st: Difference of means and t-test


From   Richard Williams <richardwilliams.ndu@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Difference of means and t-test
Date   Mon, 14 Jun 2010 12:07:51 -0500

At 04:41 PM 6/12/2010, mmolina@uniroma3.it wrote:
Dear Statalist,

I am working with three different samples.
When I deal with two of them, I can calculate the difference of means and
t-test by doing:

ttesti obs1 mean1 std1 obs2 mean2 std2, unequal

As I have three groups, I am also interested in testing the null: mean1 =
mean2 = mean3 , under the alternative that at least one mean is different.

Could you please give me some advice?

Are you using ttesti because you do NOT have the raw data? If you do have the raw data, it would be easier to use ttest and then use anova or oneway for your three means test. If you don't have the raw data, I don't think there is anything like a onewayi -- one possible approach might be to use corr2data to create a fake data set with the deisred Ns, means and standard deviations.


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Richard Williams, Notre Dame Dept of Sociology
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