Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: st: Difference of means and t-test
From
"Nick Cox" <[email protected]>
To
<[email protected]>
Subject
RE: st: Difference of means and t-test
Date
Mon, 14 Jun 2010 17:19:43 +0100
-- except that will surely overstate the strength of the conclusions, in
so far as the real distributions are unlikely to be exactly Gaussian.
Nick
[email protected]
Richard Williams
At 04:41 PM 6/12/2010, [email protected] wrote:
>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.
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/