This study examines the relative performance of Japanese cooperative banks between 1998 and 2009, explicitly modeling non-performing loans as an undesirable output. Three key findings emerge. First, the sector is characterized by increasing returns to scale which supports the ongoing...

This paper develops a novel statistic for firm efficiency called efficiency depth that allows for statistical inference in case of errors-in-variables. We derive statistical tests that require minimal statistical assumptions; neither the sample distribution nor the noise level is required. An...