Zhang and Bartels (1998) show formallyhow DEA efficiency scores are affected by sample size. They demonstratethat comparing measures of structural inefficiency between samplesof different sizes leads to biased results. This note arguesthat this type of sample size bias has much wider...

This study investigates the measurement of the efficiency of product markets by means of Data Envelopment Analysis (DEA). To demonstrate how comparing average efficiencies derived by DEA across markets may lead to conclusions driven mainly by the effects of sample size when the samples differ...

This study introduces the concept of product performance from the perspective of customers. Product performance is measured as a ratio of outputs that customers obtain from a product relative to inputs that customers have to spend for purchasing and using the product. The output side is modelled...

We analyse the efficiency of the branches of a local bank in Cologne, Germany, using a novel two-stage Data Envelopment Analysis (DEA) approach. Traditional DEA studies frequently found that most branches of a bank were efficient, which led researchers to conclude that banks are usually "well...