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re: st: PSMATCH with 2 conditions


From   "Ariel Linden, DrPH" <ariel.linden@gmail.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   re: st: PSMATCH with 2 conditions
Date   Wed, 8 Sep 2010 06:50:50 -0700

I would suggest another path to take here. cem (Coarsened Exact Matching)is
user written program by Gary King (http://gking.harvard.edu/cem/) that
allows you to force a match on a specific level of a variable (for example,
force gender to be exact). In this case, I would match some variables within
calipers and require exact matches where necessary on other variables.

I hope this helps

Ariel 

Date: Tue, 7 Sep 2010 11:07:37 -0700
From: "Caskey, Judson" <judson.caskey@anderson.ucla.edu>
Subject: re: st: PSMATCH with 2 conditions

See the following post for an example of forcing a match:

http://www.stata.com/statalist/archive/2010-09/msg00073.html

In your case, say you have a 4-digit industry code (e.g. SIC). You can first
compute propensity scores, then make a new variable pscore2 that looks like:

pscore2 = year*100000+industry*10+pscore

If you have year 1999, industry 1234 and p-score 0.25, you get:

pscore2 = 199912340.25

If you put a caliper of, say, 0.5, it is impossible to match to a firm in a
different industry/year.

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