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Re: st: Comparing results from two separate t-tests
.
I enjoyed Ithaca, when I was there!
Maybe you could use a regress instead of ttest. It will give the same
answer as ttest, if you form a dummy variable for group membership and
use it to predict your response variable. Estimates store will work
with regress. You could also move on with regress to look at both
political membership and treatment in the same model, without having
to use multiple ttests.
-Dave
On Mar 12, 2008, at 2:30 PM, Geoff Wallace wrote:
Dear All,
I have had problems trying to test for whether the treatment effects
for two groups of respondents (conservatives and liberals) in a
social science experimental questionnaire I am using are
significantly different. I used the -ttest- command to obtain the
difference of means across the treatment and control group first for
the conservative respondent subsample and then repeated the
procedure for the liberal respondent subsample. I should also note
that I used the –unpaired- option for each command since the data
are not paired. The output from the two -ttest- commands yields a
separate treatment effect for each subsample. However, I am having
trouble figuring out how to use Stata to perform a corresponding
ttest on the two separate difference of means. I tried using -est
store- after each -ttest- command, but as I expected this option
does not appear to work with –ttest-.
Any help would be much appreciated.
Best, Geoff
--
Geoffrey P.R. Wallace
Ph.D. Candidate
Department of Government
Cornell University
214 White Hall
Ithaca, NY 14850
t.202.302.4209
f.607.255.4530
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