PPMLHDFE - lgdp_o and lgdp_d not shown in results

[Micky Lu]

Dear all,

I am using ppmlhdfe command to run a gravity equation, with importer-sector and exporter-sector fixed effect. However, the lgdp_o and lgdp_d are not shown in the regression results. I would like to know if lgdp_o and lgdp_d are included into the running of the regression? What is the reason for them not being displayed?

ppmlhdfe flow ldist lgdp_o lgdp_d, noconstant absorb(imp#sector exp#sector)

Another question is that although I specified noconstant, the final table still shows constants. Why is this the case? Does it affect my coefficients?
Thank you in advance for your help.

[Joao Santos Silva]

The gdp pariables are probably collinear with the fixed effects; it does not make much sense to specify noconstant if you have fixed effects.

[Micky Lu]

The gdp pariables are probably collinear with the fixed effects; it does not make much sense to specify noconstant if you have fixed effects.

Dear Professor Joao Santos Silva,
Thank you for your explanation!