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Re: st: paired t-test on matched sample after propensity score matching


From   Neil Shephard <nshephard@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: paired t-test on matched sample after propensity score matching
Date   Fri, 14 Aug 2009 17:07:52 +0100

On Fri, Aug 14, 2009 at 4:59 PM, Weichle, Thomas<Thomas.Weichle@va.gov> wrote:
> Dear Statalisters,
> I'm trying to do a paired t-test on a matched sample after performing
> propensity score matching to assess differences in measured
> characteristics between treated and untreated individuals.  I've used
> psmatch2 to perform the matching.  I'm familiar with the syntax to do a
> paired t-test when there are 2 variables and we want to test whether
> they differ (ttest varname1 == varname2).  However, the way my data is
> set up after performing the matching doesn't have 2 separate variables.
> For example, there is 1 column for each measured characteristic, an
> indicator for treatment status, and another variable indicating which
> control the treated was matched to.  Does anyone have any experience
> trying to perform this matched individuals paired t-test?  Maybe I don't
> have my data set up correctly.

You're correct, you need to -reshape- your data first.  See -man
reshape- for more information.

Neil


-- 
"The combination of some data and an aching desire for an answer does
not ensure that a reasonable answer can be extracted from a given body
of data." ~ John Tukey (1986), "Sunset salvo". The American
Statistician 40(1).

Email - nshephard@gmail.com
Website - http://slack.ser.man.ac.uk/
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