[Jose-Luis Herrera]

Dear Gabriele,

I am new on PTF estimation. I am using the ACF aproach and began with the acfest comand which use GMM. By construction the command use the lags of the regresors for the control function of the second stage and so on some observations are lost. Instead, with prodest ACF is an option included on LP or OP methods, and all the paneldata set is consider for the estimation. Why occur that difference? is the ACF correction in prodest different than ACF aproach? Thank you very much in advance.

prodest prod, free(labor) proxy(m) state(capital) poly(3) met(lp) valueadded reps(50) acf



acfest prod, free(labor) state(capital) proxy(m) i(iruc) t(year) va


Best, Jose-Luis.

[Gabriele Rovigatti]

Dear Jose-Luis,

the analysis sample in the two cases is the same. The reported number is different, though, because prodest reports the complete dataset, including the lagged values, whereas acfest discount that - to be completely honest, I think that acfest approach is more correct, I will try to release a new version of prodest that fixes this.

Thank you very much,

Gabriele