st: Sargan test after xtdpdsys vce(robust)

[Angela C <aggela.christou@gmail.com>]

Dear All,

i am using Stata12 to analyse panel data using xtdpdsys.

While xtdpdsys and estat abond work fine, when i try to perform a
sargan test the output is as follows:

Sargan test of overidentifying restrictions
        H0: overidentifying restrictions are valid
        cannot calculate Sargan test with vce(robust)

        chi2(118)    =         .
        Prob > chi2  =         .


I cannot perform it even when i webuse abdata, just following the
manual's instructions..

Why doesn't it work on Robust Standard Errors? should i use some other command?

Other statalist topics adressing estat sargan after xtdpdsys could not help.


If anyone could please help me, i would really appreciate it!

Best Regards

Angela
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