Martínez-Zarzoso (2013) compares different estimations techniques that have been proposed in the economic literature to deal with issues concerning zero
trade values and heteroskedastic residuals. Using simulations to compare PPML, GPML, NLS and FGLS estimators, she finds that although the PPML estimator is
less affected by heteroskedasticity than others are, its performance is similar, in terms of bias and standard errors, to the FGLS estimator performance, in particular
for small samples. GPML presents however the lowest bias and standard errors in the simulations without zero values. The results of the empirical estimations,
using three different samples containing real data, indicate that the choice of estimator has to be made for each specific dataset. There is not a general “best”
estimator and it is highly recommended to follow a model selection approach using a number of tests to select the more appropriate estimator for any application