Editors' introduction

The annual issue of the Journal of Econometrics focuses on endogeneity problems in econometrics, with some emphasis on endogeneity in frontier production function models. It has been motivated by the observation that there seems to be some confusion in the literature about how to deal with endogeneity in stochastic frontier models. The issue contains papers about endogeneity in settings other than frontier models, and while most of the papers that are about frontier models deal with stochastic frontiers. There also papers about endogeneity in nonparametric deterministic frontier models.