Thanks for the suggestions. To make my problem clrear, here
> is the way my model look
>
> Y1=sellers Y2=buyers
> biprobit y1 y2 x1 x2 x3 x4 (pw=weight)
>
> Here I want to eastimate two selection parameters for both
> regimes, so that I can use them in the second step which is
> weighted two stage least square. I want to use this
> selection parameters as an instrumental variables in my
> second model, which looks like;
> ivreg y1 x1 x2 (invmills1 = x4 x5) [pweight = weight)
> ivreg y2 x1 x2 (invmills2=x4 x5) [pweight = weight)
>
> Invers mills here is the selection parameter from the
> biprobit, which considers the factors that affect the
> decision to sell and/or buy - in this case x3 x4 . This is
> what I thought if i am right, So I hope I made the problem
> clear now.
>
> thanks for your time and suggestion again.
> sami
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