Estimating efficiency effects in a panel data stochastic frontier model

This paper proposes a panel data based stochastic frontier model which accommodates time-invariant unobserved heterogeneity along with efficiency effects. The efficiency effects are specified by a standard normal cumulative distribution function of exogenous variables which ensures the efficiency scores to lie in a unit interval. The model is within-transformed and then estimated with non-linear least squares. The finite sample properties of the proposed estimator are investigated through a set of Monte Carlo experiments. The experiments suggest that our estimation procedure generally performs well also in small samples. Finally, an empirical illustration based on widely used panel data on Indian farmers reveals the simplicity and easy applicability of the model.