3.1.2 Basic type of case study design (2x2 matrix

Yin (2002) proposed the 2x2 framework which demonstrates 4 types of case study design as shown in figure 17. The vertical axis of the diagram (figure 17) represents the number of case studies which is/ are conducted (single or multiple-case design), while the horizontal axis represents how specific or deep the investigation is in each case study, the horizontal axis also consists of two types of analysis, holistic and embedded.

Figure 17: 4 types of case study design (2x2 framework), Source: Yin (2002), (own illustration)

In this research, the multiple-case design with holistic analysis is chosen as a case study strategy. One of the advantages of the multiple-case design is the comparability between cases. The comparability of distinction and similarity between each case could not be done in a single-case investigation. The holistic analysis approach is an investigation of the entire case, it is suitable when there is no logical subunit investigation needed (Yin, 2002). For this research, it is more important to investigate each case study holistically since it is mainly focused on the provided PSS regarding material leakage minimization and resource optimization, therefore, there is no deeply specific sub-unit investigation need. Also, investigation as an overview could make the researcher see the relationship of each aspect within the case study broader.