characterizing the extent of heterogeneity within an industry that is robust with regard to extreme values of a few small firms. It … was found that the level of intra-industry heterogeneity is mainly determined by an industries' average technical …

that has only partially been answered. This paper argues that heterogeneity among universities as well as persistent … heterogeneity distorts the estimation results towards lower efficiency values. The newly introduced specification improves the … accuracy of the heterogeneity assumption and exposes that inefficiency tends to be long term and persistent rather than short …

Accounting for network operators' heterogeneity is of crucial importance for regulators. In contrast to observed … heterogeneity, the consideration of unobserved differences is far more challenging. Most estimation models try to account for …, efficiency estimates may be biased as technological heterogeneity is misunderstood as inefficiency. To overcome this …

unobserved institution specific heterogeneity. While the first term reflects the efficiency of the individual universities …