Dear Stata community,


I have a panel gravity dataset. I have trying to run the following models

1. ivppml patents pc1_CS ln_gdp_o ln_gdp_d ln_wdi_gerp_qog_data_o ln_wdi_gerp_qog_data_d ln_tradeflow_baci Inst_Dist ln_dist contig comlang_off colony, inst( new_gendist_plurality ln_gdp_o ln_gdp_d ln_wdi_gerp_qog_data_o ln_wdi_gerp_qog_data_d ln_tradeflow_baci Inst_Dist ln_dist contig comlang_off colony)


what is the mistake I'm doing? when i try to include year_* origin_* and dest_* fixed effects the model does not converge. is this expected?

Array

2. I have tried ivpoisson with the following code. However, i get an error saying "Hessian is not positive semidefinite". How can i correct for this?

ivpoisson gmm patents ln_gdp_o ln_gdp_d ln_wdi_gerp_qog_data_o ln_wdi_gerp_qog_data_d ln_tradeflow_baci Inst_Dist ln_dist contig comlang_off colony ( pc1_CS = new_gendist_plurality)