hello,
I am using ppml_panel_sg to reg trade on some gravity variables and rta, finding that ppml_panel_sg cannot get the right predict values.
Then I use simplify the data,with the same data i use ppml_panel_sg and PPML to predict values respectively,finding different predict values.
like this,
code:
ppml trade PAIR_FE1-PAIR_FE$NTij_1 EXPORTER_TIME_FE* IMPORTER_TIME_FE1-IMPORTER_TIME_FE$NT_yr RTA, noconst
predict trade1,mu

ppml_panel_sg trade RTA,ex(exporter) im(importer) y(year)
predict trade2

sum trade trade1 trade2



Variable | Obs Mean Std. Dev. Min Max
-------------+---------------------------------------------------------
trade | 512 18695.41 149875.9 0 2795426
trade1 | 512 18695.41 150052.1 .0022326 2802068
trade2 | 512 .0350129 .089555 0 .2636268

apparently,trade2 is not right predicted values.

I have 2 questions:
1)is it right to get the predict values like above?
2)I get the fixed effects from ppml_panel_sg by the options genD，finding it is also different with the results of ppml.

Can someone give me some hints/explanation? thank you!!!