Case studies

Context and purpose

Yin (2009, 18) provides a technical definition of the case study as „an empirical inquiry that investigates a contemporary phenomenon in depth and within its real-life context, especially when the boundaries between phenomenon and context are not clearly evident.“ This definition makes clear that the use of case studies in research is not to be confused with the use of case studies in teaching, e. g. in the fields of law, business, medicine or public policy (Yin 2009, 4). Unlike the use of case studies in education, the purpose of the case study method in social science research is to understand complex social phenomena, based on a rigorous and fair presentation of empirical findings.

Eisenhardt defines the case study approach as „a research strategy which focuses on understanding the dynamics present within a single setting (Eisenhardt 1989, 534).“ Her definition stresses that through an in depth analysis of a single case, the researcher is able to trace „how“ and „why“ a particular social phenomenon developed. Partly because of this strength, case studies have frequently been employed to explain decisions or sets of decisions made by individuals or organizations: why were they taken, how were they implemented and what were the results (Schramm 1971)?

Analytical focus and theoretical basis

Case studies can serve explorative, descriptive and explanatory purposes. When employed for explanatory purposes, case studies can be used to test the viability of alternative hypothesis which are formulated at the outset of the empirical analysis. Eisenhardt (1989) also shows how case studies can be used in the process of inducing theory from empirical findings.

The case study method can employ multiple levels of analysis (e.g. firm vs. industry level or regional vs. national level) and multiple types of data collection. Case studies that attempt to illuminate a single outcome occurring in a bounded object are referred to as „single-outcome studies“, whereas case studies that can be generalized to a broader population of objects are referred to as „case studies“ (Gerring 2006). Of course, the analysis of multiple cases can be combined in one case study (see e.g. Leonard-Barton’s (1988) analysis of ten innovation projects).

Sources, types and processing of data

The ability to combine different data sources is described as a particular strength of the case study method vis-a-vis related methods (Yin 2009). Possible data sources include expert interviews, surveys, statistical data, (participant) observations or documents. Quantitative data (e.g. from surveys) can be combined with qualitative evidence (e. g. from expert interviews). These multiple sources of evidence can be used in a triangulating fashion in order to construct a „chain of evidence“.


Firstly, case studies seems to be particular apt to shed light on decision making processes at the early stages of the policy cycle, because they contribute to the understanding of the context in which a particular policy has evolved. For example, a case study could address the question why a specific policy option was selected over other options and which factors influenced the decision. Relevant methods and data sources in this context could be expert interviews with policy makers or content analysis of political documents. Different cases dealing with environmental legislations on the European or member state level could be combined in one case study in order to study patterns of decision making in the environmental policy realm. Secondly, case studies could be employed to address the impact of environmental policies in a holistic manner, e. g. addressing direct and indirect effects. In particular, the impact of an environmental policy on decisions made by individuals or organizations affected by this policy could be studied. .

Assessment results

The case study method could be employed to analyse the evolution of a particular policy and its wider impacts on society. Considering the different assessment categories, case studies seem to be more suitable to assess a policy’s efficacy and effectiveness. This is because efficacy and effectiveness both relate to the ability to produce a desired impact. Whether the desired policy impact can be achieved or not depends, in turn, on how the objects of the policy intervention respond to this particular intervention. Case studies can shed light on the underlying decision making processes, e. g. why do some firms trigger innovation in order to meet increasing environmental standards whereas others do not?

However, case studies might be less suited to analyse the efficiency of environmental policies on a societal level because data from case studies is sometimes difficult to generalize.

Comparison with other methods

In comparison to surveys, case studies are able to integrate more variables into the research process and to use multiple sources of evidence. In contrast to modelling approaches or social experiments case studies do not alienate social phenomena from their context, or at least to a lesser extent. However, in principle, case studies can be combined with many other social science methods, e. g. expert interviews, patent analysis, systems of innovation analysis.


Eisenhardt, K.M. 1989. Building Theory from Case Study Research. Academy of Management Review, 14 (7), pp. 532-550.

Gerring, J. 2006. Single-Outcome Studies: A Methodological Primer. International Sociology, 21, pp. 707-734.

Leonard-Barton, D. 1988. Synergistic design for case studies: Longitudinal single-site and replicated muliple-site. Paper presented at the National Science Foundation Conference on Longitudinal Research Methods in Organizations, Austin.

Schramm, W. 1971. Notes on casestudies of instructional media project. Working paper for the Academy of Educational Development, Washington D.C.

Yin, R.K. 2009. Case Study Research: Design and Methods. 4th edition, Los Angeles: Sage.