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Proc Qlim and Inverse Mills Ratio

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Proc Qlim and Inverse Mills Ratio

I got the inverse Mills ratio (imr) for all the observations from the proc qlim; however I am unable to reconcile these estimates for imr with the manual estimation where

imr=pdf('normal',pred_xb)/(1-CDF('normal',pred_xb)), if dummy=1 and

imr=-pdf('normal',pred_xb)/(cdf('normal',pred_xb), if dummy=0

qlim procedure estimates and the above estimates are different, I am not sure why, any ideas?

Another issue in relation to proc qlim, why Lambda and the coefficients on Lambda do not show on the outcome of the second equation?

Thank you

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