We propose a new inverse probability weighting (IPW) estimator for moment condition models with missing data. Our estimator is easy to implement and compares favourably with existing IPW estimators, including augmented IPW estimators, in terms of efficiency, robustness, and higher-order bias. We...

We consider a panel quantile model with fixed effects. It is shown that the maximum likelihood estimator is numerically equivalent to the least absolute deviations estimator of the differenced model, and as a consequence, there is no incidental parameter problem.