st: psmatch2 and matching within the metropolitan area

[Hui-shien Tsao <ht7651@gmail.com>]

Hi all ---

    I am using psmatch2 to conduct propensity score matching.  My data 
is a pool of cases from four metropolitan areas.  I would like to match 
the treated tracts to the untreated tracts within the same metropolitan 
area.  I have tried to create dummy variables to control for 
metropolitan areas.  However, some of the matches still pick tracts from 
a different metropolitan area.  Is there any way I can match within the 
same metropolitan area?  Thank you for your help in advance.

Hui-shien

*****
Here is my syntax:

gen random=uniform()
sort random
psmatch2 treat metro1 metro2 metro3 var1 var2 var3 var4, logit 
neighbor(1) common trim(3)

A simplified data structure:

id	metro	treat	Var1	Var2	Var3
1	1	1	1	4	4
2	1	0	2	1	3
3	1	0	3	1	1
4	1	0	3	5	2
5	1	1	2	3	5
6	2	0	1	1	3
7	2	0	1	2	8
8	2	0	2	5	6
9	2	0	3	3	3
10	2	1	3	7	1
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