Dear Joao Santos Silva
I am an undergraduate student who is researching for his thesis about the trade impact of non-tariff measures on Peruvian exports in 2016. For this purpose, and since I have a large number of zeros in my sample, I'm using the gravity model and PPML estimator as you recommend on your papers titled " The log of gravity" (2006) and "Further simulation evidence on the performance of the Poisson pseudo-maximum likelihood estimation" (2011). Also, I'm using the UNESCAP (2013) user guide in order to get the correct code to estimate my model using the PPML. However, I still have some questions about your estimator and its results.
1) My dataset contains 50 importer fixed-effects and 21 HS sector fixed-effects. Is it correct to include very high fixed effects into PPML estimations? Do I have to use the ppmlhdfe estimator? Is it any difference between ppml with high fixed effects and ppmlhdfe estimator?
2) The outcome table (after 11 iterations) presents a warning message which says that I need to rescale the lnPIB_reporter variable (which is in million of dollars). Does it have any consequence if I don't rescale the above variable?
3) Is it neccessary to turn on the "option strict"?
Finally, I was wondering if you can share me the stata code of your 2011 paper to observe how to estimate the ET Tobit and GPML estimator. I want to use them in my robustness check.
Best,
Juan Quicana
Pd: I attach my stata code
I am an undergraduate student who is researching for his thesis about the trade impact of non-tariff measures on Peruvian exports in 2016. For this purpose, and since I have a large number of zeros in my sample, I'm using the gravity model and PPML estimator as you recommend on your papers titled " The log of gravity" (2006) and "Further simulation evidence on the performance of the Poisson pseudo-maximum likelihood estimation" (2011). Also, I'm using the UNESCAP (2013) user guide in order to get the correct code to estimate my model using the PPML. However, I still have some questions about your estimator and its results.
1) My dataset contains 50 importer fixed-effects and 21 HS sector fixed-effects. Is it correct to include very high fixed effects into PPML estimations? Do I have to use the ppmlhdfe estimator? Is it any difference between ppml with high fixed effects and ppmlhdfe estimator?
2) The outcome table (after 11 iterations) presents a warning message which says that I need to rescale the lnPIB_reporter variable (which is in million of dollars). Does it have any consequence if I don't rescale the above variable?
3) Is it neccessary to turn on the "option strict"?
Finally, I was wondering if you can share me the stata code of your 2011 paper to observe how to estimate the ET Tobit and GPML estimator. I want to use them in my robustness check.
Best,
Juan Quicana
Pd: I attach my stata code
Code:
ppml exports lnPBI_partner lnPBI_reporter lnDistancia frontera lenguaje colonia ALC mediterraneo ln_arancel MNA_dummy exp_dum_* imp_dum_* seccion_dum_*, cluster(distancia)
Comment