Case study

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A case study is a research strategy, sometimes likened to an experiment, a history, or a simulation, though not linked to any particular type of evidence or method of data collection (Yin 2003). It is not qualitative research, as is often confused by laymen.

Rather than using large samples and following a rigid protocol to examine a limited number of variables, case study methods involve an in-depth, longitudinal examination of a single instance or event: a case. They provide a systematic way of looking at events, collecting data, analyzing information, and reporting the results. As a result the researcher may gain a sharpened understanding of why the instance happened as it did, and what might become important to look at more extensively in future research. Case studies lend themselves to both generating and testing hypotheses (Flyvbjerg, 2006).

Yin, on the other hand, suggests that case study should be defined as a research strategy, an empirical inquiry that investigates a phenomenon within its real-life context. Case study research means single- and multiple case studies, can include quantitative evidence, relies on multiple sources of evidence and benefits from the prior development of theoretical propositions. He notes that case studies should not be confused with qualitative research and points out that they can be based on any mix of quantitative and qualitative evidence (Yin, 2002). This is also supported and well-formulated in (Lamnek, 2005): "The case study is a research approach, situated between concrete data taking technique and methodologic paradigma".

The scope and relevance of case studies

Certain disciplines thrive on case studies: others find them less suitable in given situations. Compare usage and perceived validity in the humanities, natural sciences, social sciences, pseudoscience and business.

Rogers, in Business Analysis for Marketing Managers (1978) distinguishes case studies from case histories and projects. He describes a case history as an event or series of events set in an organisational framework with or without a related environment. The events are described in some detail with the main and subsidiary points highlighted. Actions taken by subjects in the case are described; reactions, responses and effects on other subjects are related, and events taken to a conclusion or to a point that is irreversible. Medical cases are typical of the category. Symptoms are described, probable and possible causes suggested, treatment recommended, prognosis recorded, and the date when the patient was discharged or buried.

He defined the case study as also describing events in a framework within an environment. The problems are not always highlighted or even made clear; they emerge as the case material is subjected to analysis. A conclusion is not necessarily stated nor is the situation reached in the case irreversible. It is usually possible to ‘take over’ operations at a suitable point in the role of an external adviser or from a position in the case. Most business cases fall into this category.

The case project is a series of diverse continuous events, set in an organizational framework and normally in a well-defined environment. Those studying the case are led to a specific point in time and circumstance where they become a ‘participant’ in the case. They may be asked to assume the role of a person in the case, appointed to a particular vacancy, or to advise from the position of an external consultant. The role is made explicit and it is from that viewpoint that analysis, views, arguments and recommendations must be made; there is thus a behavioural aspect introduced. If placed in the position of a newly appointed middle manager, responses and suggestions are likely to be different from those of an external consultant. Rogers developed the case project in 1966 for the Chartered Institute of Marketing’s diploma final open book examination. To avoid pre-prepared scripts being submitted, the examination paper progressed the case by several months from when it was published, introducing new material. This required candidates to modify the analyses and conclusions already reached and write a true examination room report.

Types of case study

Illustrative case studies

Illustrative case studies describe a domain; they use one or two instances to analyze a situation. This helps interpret other data, especially when researchers have reason to believe that readers know too little about a program. These case studies serve to make the unfamiliar familiar, and give readers a common language about the topic. The chosen site should typify important variations and contain a small number of cases to sustain readers' interest.

The presentation of illustrative case studies may involve some pitfalls. Such studies require presentation of in-depth information on each illustration; but the researcher may lack time on-site for in-depth examination. The most serious problem involves the selection of instances. The case(s) must adequately represent the situation or program. Where significant diversity exists, no single individual site may cover it.

Exploratory case studies

Exploratory case studies condense the case study process: researchers may undertake them before implementing a large-scale investigation. Where considerable uncertainty exists about program operations, goals, and results, exploratory case studies help identify questions, select measurement constructs, and develop measures; they also serve to safeguard investment in larger studies.

The greatest pitfall in the exploratory study involves premature conclusions: the findings may seem convincing enough for inappropriate release as conclusions. Other pitfalls include the tendency to extend the exploratory phase, and inadequate representation of diversity.

Critical instance case studies

Critical instance case studies examine one or a few sites for one of two purposes. A very frequent application involves the examination of a situation of unique interest, with little or no interest in generalizability. A second, rarer, application entails calling into question a highly generalized or universal assertion and testing it by examining one instance. This method particularly suits answering cause-and-effect questions about the instance of concern.

Inadequate specification of the evaluation question forms the most serious pitfall in this type of study. Correct application of the critical instance case study crucially involves probing the underlying concerns in a request.

Program implementation case studies

Program implementation case studies help discern whether implementation complies with intent. These case studies may also prove useful when concern exists about implementation problems. Extensive, longitudinal reports of what has happened over time can set a context for interpreting a finding of implementation variability. In either case, researchers aim for generalization and must carefully negotiate the evaluation questions with their customer.

Good program implementation case studies must invest sufficient time to obtain longitudinal data and breadth of information. They typically require multiple sites to answer program implementation questions; this imposes demands on training and supervision needed for quality control. The demands of data management, quality control, validation procedures, and analytic modelling (within site, cross-site, etc.) may lead to cutting too many corners to maintain quality.

Program effects case studies

Program effects case studies can determine the impact of programs and provide inferences about reasons for success or failure. As with program implementation case studies, the evaluation questions usually require generalizability and, for a highly diverse program, it may become difficult to answer the questions adequately and retain a manageable number of sites. But methodological solutions to this problem exist. One approach involves first conducting the case studies in sites chosen for their representativeness, then verifying these findings through examination of administrative data, prior reports, or a survey. Another solution involves using other methods first. After identifying findings of specific interest, researchers may then implement case studies in selected sites to maximize the usefulness of the information.

Prospective case studies

Case studies can be used not only for inductive theory development, but also as quasi-experiments in deductive theory testing. In a prospective case study design, the researcher formulates a set of theory-based hypotheses in respect to the evolution of an on-going social or cultural process and then tests these hypotheses at a pre-determined follow-up time in the future by comparing these hypotheses with the observed process outcomes using "pattern matching" (Campbell, 1966; Trochim, 1989) or a similar technique. This prospective research design consists of (1) a baseline case study, which is used to formulate a set of hypotheses in respect to the evolving social process (i.e., "What predictions would a given theory make in respect to this process?"), establish the follow-up time, follow-up study methodology, and outcome evaluation criteria; and (2) of a follow-up case study conducted at the predetermined follow-up time. In this follow-up study, the formulated hypotheses are compared to the observed outcomes of the social process, and the predictive power of the theory is, thus, evaluated.

Cumulative case studies

Cumulative case studies aggregate information from several sites collected at different times. The cumulative case study can have a retrospective focus, collecting information across studies done in the past, or a prospective outlook, structuring a series of investigations for different times in the future. Retrospective cumulation allows generalization without cost and time of conducting numerous new case studies; prospective cumulation also allows generalization without unmanageably large numbers of cases in process at any one time.

The techniques for ensuring sufficient comparability and quality and for aggregating the information constitute the "cumulative" part of the methodology. Features of the cumulative case study include the case survey method (used as a means of aggregating findings) and backfill techniques. The latter aid in retrospective cumulation as a means of obtaining information from authors that permits use of otherwise insufficiently detailed case studies.

Opinions vary as to the credibility of cumulative case studies for answering program implementation and effects questions. One authority notes that publication biases may favor programs that seem to work, which could lead to a misleading positive view (Berger, 1983). Others raise concerns about problems in verifying the quality of the original data and analyses (Yin, 1989).

Narrative case studies

Case studies that present findings in a narrative format are called narrative case studies. This involves presenting the case study as events in an unfolding plot with actors and actions.

Medical case studies

In medical science case studies are considered "Class V" evidence, and are thus the least suggestive of all forms of medical evidence.[1]

Embedded case studies

A case study containing more than one sub-unit of analysis is referred to as an embedded case study (Yin, 2002).

Case selection

When selecting a case for a case study, researchers often use information-oriented sampling, as opposed to random sampling (Flyvbjerg, 2006). This is because the typical or average case is often not the richest in information. Extreme or atypical cases often reveal more information because they activate more basic mechanisms and more actors in the situation studied. In addition, from both an understanding-oriented and an action-oriented perspective, it is often more important to clarify the deeper causes behind a given problem and its consequences than to describe the symptoms of the problem and how frequently they occur. Random samples emphasizing representativeness will seldom be able to produce this kind of insight; it is more appropriate to select some few cases chosen for their validity.

The following three types of information-oriented cases may be distinguished: (1) Extreme or deviant cases, (2) Critical cases, and (3) Paradigmatic cases.

The extreme case can be well-suited for getting a point across in an especially dramatic way, which often occurs for well-known case studies such as Freud’s ‘Wolf-Man.’

A critical case can be defined as having strategic importance in relation to the general problem. For example, an occupational medicine clinic wanted to investigate whether people working with organic solvents suffered brain damage. Instead of choosing a representative sample among all those enterprises in the clinic’s area that used organic solvents, the clinic strategically located a single workplace where all safety regulations on cleanliness, air quality, and the like, had been fulfilled. This model enterprise became a critical case: if brain damage related to organic solvents could be found at this particular facility, then it was likely that the same problem would exist at other enterprises which were less careful with safety regulations for organic solvents. Via this type of strategic sampling, one can save both time and money in researching a given problem. Another example of critical case sampling is the strategic selection of lead and feather for the test of whether different objects fall with equal velocity. The selection of materials provided the possibility to formulate a generalization characteristic of critical cases, a generalization of the sort, ‘If it is valid for this case, it is valid for all (or many) cases.’ In its negative form, the generalization would be, ‘If it is not valid for this case, then it is not valid for any (or only few) cases.’

A paradigmatic case may be defined as an exemplar or prototype. Thomas Kuhn has shown that the basic skills, or background practices, of natural scientists are organized in terms of ‘exemplars’ or 'paradigms' the role of which in the scientific process can be analyzed. Similarly, scholars like Clifford Geertz and Michel Foucault have often organized their research around specific cultural paradigms: a paradigm for Geertz lay for instance in the ‘deep play’ of the Balinese cockfight, while for Foucault, European prisons and the ‘Panopticon’ are examples. Both instances are examples of paradigmatic cases, that is, cases that highlight more general characteristics of the societies or issues in question. Kuhn has shown that scientific paradigms cannot be expressed as rules or theories. There exists no predictive theory for how predictive theory comes about. A scientific activity is acknowledged or rejected as good science by how close it is to one or more exemplars; that is, practical prototypes of good scientific work. A paradigmatic case of how scientists do science is precisely such a prototype. It operates as a reference point and may function as a focus for the founding of schools of thought.

Careful case selection may help generalizing from case studies (see next section).

For more on case selection, see [2]

Generalizing from case studies

The case study is effective for generalizing using the type of test that Karl Popper called falsification, which forms part of critical reflexivity (Flyvbjerg, 2006). Falsification is one of the most rigorous tests to which a scientific proposition can be subjected: if just one observation does not fit with the proposition it is considered not valid generally and must therefore be either revised or rejected. Popper himself used the now famous example of, "All swans are white," and proposed that just one observation of a single black swan would falsify this proposition and in this way have general significance and stimulate further investigations and theory-building. The case study is well suited for identifying "black swans" because of its in-depth approach: what appears to be "white" often turns out on closer examination to be "black."

For instance, Galileo’s rejection of Aristotle’s law of gravity was based on a case study selected by information-oriented sampling and not random sampling. The rejection consisted primarily of a conceptual experiment and later on of a practical one. These experiments, with the benefit of hindsight, are self-evident. Nevertheless, Aristotle’s incorrect view of gravity dominated scientific inquiry for nearly two thousand years before it was falsified. In his experimental thinking, Galileo reasoned as follows: if two objects with the same weight are released from the same height at the same time, they will hit the ground simultaneously, having fallen at the same speed. If the two objects are then stuck together into one, this object will have double the weight and will according to the Aristotelian view therefore fall faster than the two individual objects. This conclusion seemed contradictory to Galileo. The only way to avoid the contradiction was to eliminate weight as a determinant factor for acceleration in free fall. And that was what Galileo did. Historians of science continue to discuss whether Galileo actually carried out the famous experiment from the leaning tower of Pisa, or whether it is simply a myth. In any event, Galileo’s experimentalism did not involve a large random sample of trials of objects falling from a wide range of randomly selected heights under varying wind conditions, and so on. Rather, it was a matter of a single experiment, that is, a case study, if any experiment was conducted at all.

Galileo’s view continued to be subjected to doubt, however, and the Aristotelian view was not finally rejected until half a century later, with the invention of the air pump. The air pump made it possible to conduct the ultimate experiment, known by every pupil, whereby a coin or a piece of lead inside a vacuum tube falls with the same speed as a feather. After this experiment, Aristotle’s view could be maintained no longer. What is especially worth noting, however, is that the matter was settled by an individual case due to the clever choice of the extremes of metal and feather. One might call it a critical case: for if Galileo’s thesis held for these materials, it could be expected to be valid for all or a large range of materials. Random and large samples were at no time part of the picture. Most skilled scientists simply do not work this way with this type of problem.

By selecting cases strategically in this manner one may arrive at case studies that allow generalization.

For more on generalizing from case studies, see [3]

History of the case study

As a distinct approach to research, use of the case study originated only in the early 20th century. The Oxford English Dictionary traces the phrase case study or case-study back as far as 1934, after the establishment of the concept of a case history in medicine.

The use of case studies for the creation of new theory in social sciences has been further developed by the sociologists Barney Glaser and Anselm Strauss who presented their research method, Grounded theory, in 1967.

The popularity of case studies as research tools has developed only in recent decades. One of the areas in which case studies have been gaining popularity is education and in particular educational evaluation. Some of the prominent scholars in educational case study are Robert Stake and Jan Nespor (see references). Case studies have, of course, also been used as a teaching method and as part of professional development. They are well-known in business and legal education. The problem-based learning (PBL) movement is one of the examples. When used in (non-business) education and professional development, case studies are often referred to as critical incidents (see David Tripp in references).

History of Business Cases. - When the Harvard Business School was started, the faculty quickly realized that there were no textbooks suitable to a graduate program in business. Their first solution to this problem was to interview leading practioners of business and to write detailed accounts of what these managers were doing. Of course the professors could not present these cases as practices to be emulated because there were no criteria available for determining what would succeed and what would not succeed. So the professors instructed their students to read the cases and to come to class prepared to discuss the cases and to offer recommendations for appropriate courses of action. Basically that is the model still being used. See a critique of this approach.

Conclusions

The case study offers a method of learning about a complex instance through extensive description and contextual analysis. The product articulates why the instance occurred as it did, and what one might usefully explore in similar situations.

Case studies can generate a great deal of data that may defy straightforward analysis. For details on conducting a case study, especially with regard to data collection and analysis, see the references listed below.

Sources and further readings

Bent Flyvbjerg, "Five Misunderstandings About Case Study Research." Qualitative Inquiry, vol. 12, no. 2, April 2006, pp. 219-245. [4]

Siegfried Lamnek. Qualitative Sozialforschung. Lehrbuch. 4. Auflage. Beltz Verlag. Weihnhein, Basel, 2005

Charles C. Ragin and Howard S. Becker, eds., What is a Case? Exploring the Foundations of Social Inquiry (Cambridge: Cambridge University Press, 1992). [5]

Roland W. Scholz and Olaf Tietje. Embedded Case Study Methods. Integrating Quantitative and Qualitative Knowledge. Sage Publications. Thousand Oaks 2002, Sage. ISBN 0761919465

Robert E. Stake, The Art of Case Study Research (Thousand Oaks: Sage, 1995). [6]

Robert K. Yin. Case Study Research. Design and Methods. Third Edition. Applied social research method series Volume 5. Sage Publications. California, 2002. ISBN 0-7619-2553-8