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.