Appendix B
A four-stage series network, composed of three main laboratories processes (pre-testing, testing, and post-testing), is shown in Fig. 1. It actually simulates a medical diagnostic lab in the real world. The rectangles in the form of dashed line show three processes (pre-testing, testing and post-testing). In this section, we develop a four-stage network DEA model, shown in Fig.1. Suppose a set of n homogeneous DMUs denoted by\(\mathrm{\text{DMU}}_{j}\mathrm{\ }\left(j=1,2,...,\ n\right)\). The pre-test process consists of two steps called the reception unit and the sampling unit. In the process of testing, there is a stage called the test unit. Finally, in the post-test process, there is a stage called the results test unit.