1. De waarde van diagnostische bevindingen

This chapter presents some basic DEA models that are used to determine the best-practice frontier characterized by (Sect. 1.1) in Chap. 1. These models are called envelopment models, because the identified best-practice frontier envelops all the observations (DMUs). The shapes of best-practice (or efficient) frontiers obtained from these models can be associated with the concept of Returns-to-Scale (RTS) which will be discussed in details in Chap. 13. This is because the best-practice (or efficient) frontiers can be viewed as exhibiting of various types of RTS. However, if the inputs and outputs are not related to a “production function”, RTS concept cannot be applied. Under such cases, RTS is merely used to refer to different shapes of frontiers.