st: propensity score matching with caliper

[Scott Strassels <scotts1@mail.utexas.edu>]

Hello everyone,

I have a question about propensity score matching using psmatch2 with Stata 11.  I've been digging through the literature and Statalist archives on the topic without much luck.  I think I'm using psmatch2 like other authors have, but I don't understand the results.

My colleagues and I have already generated the propensity score.  Here's what I've been doing:

set seed 1000

. gen x = uniform()

. sort x

. psmatch2 treatm, pscore(propen) neighbor(1) ate noreplace caliper (0.15)

. sort _id

. gen match = id[_n1]
(309 missing values generated)


. gen treat = id if _nn == 1
(309 missing values generated)

. drop if treat == .
(309 observations deleted)

. save "/Users/scott/Desktop/propensity/Pali vs Ris caliper 022310.dta", replace
(note: dataset contains 0 observations)

Any suggestions would be very much appreciated.

Thanks,

Scott


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