the treatment effect is the difference between Y if it were true that
the treatment variable was 1 and Y if the treatment variable were 0.
the ATT is the average of those estimates over all treated (treatment =
1) units.
this part of the MatchIt manual has a discussion:
http://gking.harvard.edu/matchit/docs/Examples2.html
Gary
---
http://gking.harvard.edu
On 10/17/2009 11:57 PM, Sinan Gemici wrote:
Hi there,
In my previous posting about using survey weights I referred to log-linear analysis as a
parametric test, which was of course wrong - I shouldn't be working on a Saturday
night :)
Anyway, I've just started to teach myself about PSM and have a question about my
output for ATT:
Mean Values of Observed Data (n = 264)
Pooled Expected Values: E(Y|X)
mean sd 2.5% 97.5%
3.9676 0.5416 2.9361 5.0558
Pooled Average Treatment Effect for the Treated: Y - EV
mean sd 2.5% 97.5%
0.26723 0.07029 0.12872 0.39879
How do I turn this output into a value for ATT? Does this basically boil down to a
t-test? I know this is really basic but I don't understand.
~Sinan
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