hi all--
the verdict is really out on the role of those baseline, pre-treatment
measures of the dependent variable
Chris Winship and his collaborators have a paper on the topic that I saw
presented
and they (the variables, not Chris!) certainly seem like colliders if
there's autocorrelation
i know from a econometric perspective including lagged dependent variables
as a covariate can be a problem
I've grown to feel a bit like this is an area where "damned if you do,
damned if you don't" applies
/m
Stuart, Elizabeth A. wrote:
Hi Casey,
Matching on the outcome is certainly problematic....imagine if you got
perfect balance (which you would hope to do), then that would also imply a 0
treatment effect!
What wouldn’t be problematic (and in fact would be good) is if they were
actually matching on a pre-treatment measure of the outcome. E.g., in
education studies there is often pre-treatment test scores available, where
those same tests form the outcome value as well (but then measured
post-treatment). This kind of matching on the outcome variables (but
measured before the treatment) can be very effective.
Thanks
Liz
On 7/27/09 2:56 PM, "Casey Klofstad" <klofstad(a)gmail.com> wrote:
Hey all-
In a paper I'm reviewing one of the covariates used in a 1-to-1
matching procedure ends up also being used as the dependent variable
in the final analysis. From a theoretical point of view this seems
odd, since the variable is being treated as both a pre- and
post-treatment variable. But, is there any empirical reason to be
worried about this?
Thanks much,
-c
--
Casey A. Klofstad
University of Miami
Department of Political Science
Coral Gables, FL
klofstad(a)gmail.com
http://www.as.miami.edu/personal/cklofstad/
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