st: Comparing results from two separate t-tests

[Geoff Wallace <gw46@cornell.edu>]

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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