Daniel,
Thanks a lot for your help and explanation, it works.
Patricia
--- "Millimet, Daniel" <[email protected]> escribi�:
> You should sort the data randomly before calling
> psmatch2...
>
> set seed 123456
> gen u=uniform()
> sort u
> psmatch2 ...
>
> since there are identical propensity scores, if you call
> psmatch2 several times with data sorted in different
> orders you will get different answers since the matched
> pairs will differ. As long as the data are sorted
> randomly each time, and the other assumptions required by
> matching apply, each estimate is a consistent estimate of
> the ATT, even though they differ. By setting the seed
> and sorting the data randomly, you ensure you can
> replicate your results later.
>
> Dann
>
>
> ****************************************************
> Daniel L. Millimet, Associate Professor
> Department of Economics
> Box 0496
> SMU
> Dallas, TX USA
> phone: 214.768.3269
> fax: 214.768.1821
> web: http://faculty.smu.edu/millimet
> ****************************************************
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf
> Of Patricia Vera Rojas
> Sent: Wednesday, August 31, 2005 12:31 AM
> To: [email protected]
> Subject: st: psmatch2
>
> Hi,
>
> I have used "psmatch2" (Matching Method = neighbor) and
> I've got:
>
> "There are observations with identical propensity score
> values.The sort order of the data could affect your
> results.Make sure that the sort order is random before
> calling psmatch2"
>
> What can I do to be sure the ATT shown is correct?
>
> Thanks,
> Patricia
>
>
>
>
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______________________________________________
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*
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