Hello everyone 
I am currently running a ppml estimation, based on the theoretical model from the paper Beine, M., & Parsons, C. (2015). Climatic factors as determinants of international migration. The Scandinavian Journal of Economics, 117(2), 723-767.
I am trying to replicate their estimation, but using a different kind of shock (not climate shocks for me).
I have 47,643 observations, with bilateral panel data. More precisely, i have country of origin of migrants, country of destination, and year.
I need to control for country of origin et country of destination*year.
In that way, my command is as follow:
xi i.countryO
xi i.countryD*i.year
set matsize 2000
ppml migrantsflows GDPratio Network CW1 DependencyRatioOrigin Violence dist contig comlang_ethno _IcountryD_* _IcouXyea_*
The problem is, for every command that i tried, stata post "Number of regressors excluded to ensure that the estimates exist: x", for example with this regression "x" is 324.
Stata excludes many of my variables created by my fixed effects. I really don't understand why, i tried to find a particular pattern about this exclusion but didn't find any.
Do you have any idea about what is going on there?
NB: I know that my true model should be: ppml migrantsflows_log GDPratio_log Network_log CW1_log DependencyRatioOrigin_log Violence_log dist contig comlang_ethno _IcountryD_* _IcouXyea_*
But i have some issues with that regression. As I am using for my migrantsflows variable the difference between the ratio of emigrants from country O to countryD on the total natives in countryO, through time, I have only values <1, so my log variable is <0, and stata then post "no observations" (i guess it's because of this <0 flows issue).
Thank you in advance, i'm deeply lost with PPML!
Killian
I am currently running a ppml estimation, based on the theoretical model from the paper Beine, M., & Parsons, C. (2015). Climatic factors as determinants of international migration. The Scandinavian Journal of Economics, 117(2), 723-767.
I am trying to replicate their estimation, but using a different kind of shock (not climate shocks for me).
I have 47,643 observations, with bilateral panel data. More precisely, i have country of origin of migrants, country of destination, and year.
I need to control for country of origin et country of destination*year.
In that way, my command is as follow:
xi i.countryO
xi i.countryD*i.year
set matsize 2000
ppml migrantsflows GDPratio Network CW1 DependencyRatioOrigin Violence dist contig comlang_ethno _IcountryD_* _IcouXyea_*
The problem is, for every command that i tried, stata post "Number of regressors excluded to ensure that the estimates exist: x", for example with this regression "x" is 324.
Stata excludes many of my variables created by my fixed effects. I really don't understand why, i tried to find a particular pattern about this exclusion but didn't find any.
Do you have any idea about what is going on there?
NB: I know that my true model should be: ppml migrantsflows_log GDPratio_log Network_log CW1_log DependencyRatioOrigin_log Violence_log dist contig comlang_ethno _IcountryD_* _IcouXyea_*
But i have some issues with that regression. As I am using for my migrantsflows variable the difference between the ratio of emigrants from country O to countryD on the total natives in countryO, through time, I have only values <1, so my log variable is <0, and stata then post "no observations" (i guess it's because of this <0 flows issue).
Thank you in advance, i'm deeply lost with PPML!
Killian
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