A case study serves the purpose of verifying findings from the theory on the basis of a concrete case or to obtain new ones. A case study thus refers to a case.
Case studies basically answer explorative, descriptive and/or explanatory questions. The strengths of a case study, compared to quantitative data collection, lie in the more comprehensive mapping of social reality and the capturing of phenomena in context. This makes it possible to reconstruct developments, processes and cause-effect relationships and to make practice-relevant, data-based statements.
Case studies fall into two categories: the single case study and the comparative case study. The single case study examines exactly one case. In doing so, the researcher looks at critical, extreme, unique, representative, typical, or previously inaccessible cases. Or she observes the latter over a longer period of time. The comparative case study examines several cases and compares them with each other. The advantage lies in the critical examination of gained knowledge through similarities and differences between the cases. This makes the results more robust, trustworthy and reliable. However, it is also accompanied by a higher effort.
In contrast to quantitative methods, case studies do not allow statistical induction to a population.
Case studies are used in new or complex fields of research to develop a better picture of the situation, to separate the essential from the unessential, to abstract and to trace back supposedly new things to the known. But also in the case of advanced research, case studies provide new perspectives on the research field and thus impulses for further research. Case studies also lend themselves to quantitative research. Example: Clusters or outliers require closer examination, to support the generation of hypotheses, or validation of constructs.
The goal is to gain theoretical insights into previously unexplored phenomena.
Within the planning process, the research protocol is developed and written down, in which the further progress of the investigation is defined. The implementation is carried out as follows:
- The problem definition identifies the facts to be investigated. Within the objective of the analysis, it is determined whether the analysis makes or tests hypotheses, and, based on this, the theory-guided procedure is selected using relevant literature. The definition and selection of cases determine if a single case study or a comparative case study is carried out. The cases can be chosen at will but must be related to the research objective, and the selection must be justified. There is no need for random selection as in quantitative research. When selecting the data collection methods, they are set in relation to the case at hand and chosen accordingly. Within the comparative case study, a replication logic is applied.
- Further cases are selected so that they correspond to the framework of the first case or cases analyzed so that they are likely to confirm the previous findings (lateral replication).
- Alternatively, cases can be selected in which different results are obtained, but which are predictable in theory (theoretical replication).
- At the end of the planning process, an exemplary study (pilot case) is carried out.
What are the sources of error?
In articles, it happens that in qualitative studies, an N emerges. This N is supposed to indicate the number of studies. In the case of a qualitative research method, this information is not meaningful, as no quantitative analysis is carried out.
- Yin, R.K. (2014): Case Study Research: Design and Methods. (5th ed.), Sage Publications, Los Angeles [u.a.] 2014.
- Borchardt, A.; Göthlich, S.E. (2009): Erkenntnisgewinnung durch Fallstudien. In Albers, S.; Klapper, D.; Konradt, U.; Walter, A.; Wolf, J. (Eds), Methodik der empirischen Forschung (pp.33-48). Wiesbaden: Gabler.