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Re: st: is there a -regress- command equivalent to the pair matched ttest?


From   Richard Goldstein <richgold@ix.netcom.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: is there a -regress- command equivalent to the pair matched ttest?
Date   Mon, 08 Dec 2008 21:10:13 -0500

While your question is not completely clear, try this; after reshaping to wide form, form a new variable that is the difference between the matched pairs on your variable of interest; if you then regress with only the constant on the right you will have exactly the paired t-test results (try it); you can then add other predictors to the regress command.

Rich

josemaria wrote:
Dear Statalisters:
I am not sure whether it makes sense or not, but is there a sort of -regress- command that allows to conduct a pair-matched -ttest-, but with other independent variables?
I tried using -xtmixed-, but the result is not the same.
A contrived data set could be:
matching_identification  outcome ocasion variable_not_matched
                       1            1                1                0
                       1            2                2                0
                       2            3                1                0
                       2            5                2                1
                       3            2                1                0
                       3            4                2                1
                       4            6                1                1
                       4            5                2                1
To perform the pair-matched ttest it is necessary to -reshape- and to use -ttest outcome1==outcome2-, losing the independent variable_not_matched.
Thank for any orientation.
Regards,
José Maria

Jose Maria Pacheco de Souza, Professor Titular (aposentado)
Departamento de Epidemiologia/Faculdade de Saude Publica, USP
Av. Dr. Arnaldo, 715
01246-904  -  S. Paulo/SP - Brasil
fones (11)3061-7747; (11)3768-8612
fax (11)3714-2403
www.fsp.usp.br/~jmpsouza
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