The literature for this week focused on a case study approach. Scholars generally define case study approach as an intensive study of a single case in order to develop explanations generalizable to a larger group of cases (Gerring 2004). This particular approach provides numerous opportunities to scholars. First of all, process tracing allows to achieve conceptual validity in research. While most quantitative research methods perform conceptual stretching, in case study research scholars have an opportunity to conduct a detailed study of a single unit and carefully identify/measure the concepts involved. Secondly, case study approach is good for putting forward new hypotheses based on the exploration of outliers and deviant cases. Finally, case studies allow to examine causal mechanisms, model and evaluate causal relationships (George and Bennett 2005). I believe they are an important approach to use in research, despite their limitations, which are typical for most qualitative methods approaches. Process tracing is one of the methods used in case studies that involves “systematic examination of diagnostic evidence selected and analyzed in light of research questions and hypotheses posed…” (Collier 2011, 823). In process tracing, scholars put forward hypotheses based on having background knowledge of the phenomena under study. Process tracing allows to examine processes in great detail and collect evidence of the potential causal relationships between variables. The inferences of causal relationships in process tracing are reached by comparing and contrasting cases. Process tracing with the goal of making causal inferences involves performing different types of tests. Collier (2011) distinguishes among four basic types of empirical tests that differ based on how well they satisfy the necessary and sufficient clauses of making the causal inference acceptable. George and Bennett (2005) also see process tracing as an important method in identifying causal mechanisms. I think using process tracing as a tool of comparative research involves certain advantages and disadvantages. The main benefit of process tracing is the leverage it brings to the quantitative analysis. It allows to explore the processes from within and to provide support for causal inferences in research designs involving a small number of cases. At the same time, process tracing involves certain challenges for a researcher, such as selecting an appropriate test of causal inference, the difficulty of being able to measure and evaluate a relationship with qualitative techniques. The possibility of existing missing variables also can pose challenges for a researcher (Collier 2011). In my opinion, case studies in general and process tracing in particular are important qualitative tools that can serve as additional leverage in making causal inferences. However, selecting these techniques as part of a research design depends on the nature of research and the availability of resources. It might be impossible or simply costly to observe a process/phenomenon over a period of time before making descriptive inferences and putting forward hypotheses. I also believe that process tracing alone cannot produce reliable causal inferences in social sciences, unless certain quantitative data are also used in the process of making inferences. For example, the described method of elimination in process tracing may not be sufficient in making conclusions about causal relationships. A large number of alternative hypotheses explaining a certain relationship can be a challenge for the process tracing method and would require other additional qualitative and/or quantitative tools of research.