Hello everyone,
I estimate a gravity model with the following stata code:
ivpoisson gmm imports (immigsh = immigsh10) lnGDP_o lnGDP_d lnpop10_o lnpop10_d lndistw1990 lndistw1995 lndistw2000 lndistw2005 lndistw2010 lndistw2015 border comlang_off comlang_ethno comcol rta2 sumlandlocked tdiff comcur2 lnarea_o lnarea_d orig dest, vce(cluster pairid)
I get this error message: Hessian is not positive semidefinite
Could someone help me to understand and overcome this problem ?
Best regards,
Morel
I estimate a gravity model with the following stata code:
ivpoisson gmm imports (immigsh = immigsh10) lnGDP_o lnGDP_d lnpop10_o lnpop10_d lndistw1990 lndistw1995 lndistw2000 lndistw2005 lndistw2010 lndistw2015 border comlang_off comlang_ethno comcol rta2 sumlandlocked tdiff comcur2 lnarea_o lnarea_d orig dest, vce(cluster pairid)
I get this error message: Hessian is not positive semidefinite
Could someone help me to understand and overcome this problem ?
Best regards,
Morel
