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Strengths and Limitations of Case Studies

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Because of its strengths, case study is a particularly appealing design for applied fields of study such as education, social work, administration, health, and so on. An applied field's processes, problems, and programs can be examined to bring about understanding that in turn can affect and perhaps even improve practice. Case study has proven particularly useful for studying educational innovations, evaluating programs, and informing policy.



The posting below looks at, as the title suggests, the strengths and limitations of case studies research.  It is from Chapter 3, Qualitative Case Study Reseaarch in the book Qualitative Research: A Guide to Design and Implementation by Sharan B. Merriam.   Revised and Expanded from Qualitative Research and Case Study Applications in Education.    Copyright 2009 by John Wiley & Sons Inc. [ ] All rights reserved.  Published by Jossey-Bass A Wiley Imprint 989 Market Street, San Francisco, CA 94103-1741.


Rick Reis

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Strengths and Limitations of Case Studies


All research designs can be discussed in terms of their relative strengths and limitations. The merits of a particular design are inherently related to the rationale for selecting it as the most appropriate plan for addressing the research problem. One strength of an experimental design, for example, is the predictive nature of the research findings. Because of the tightly controlled conditions, random sampling, and use of statistical probabilities, it is theoretically possible to predict behavior in similar settings without actually observing that behavior. Likewise, if a researcher needs information about the characteristics of a given population or area of interest, a descriptive study is in order. Results, however, would be limited to describing the phenomenon rather than predicting future behavior.

Thus a researcher selects a case study design because of the nature of the research problem and the questions being asked. Case study is the best plan for answering the research questions; its strengths outweigh its limitations. The case study offers a means of investigating complex social units consisting of multiple variables of potential importance in understanding the phenomenon. Anchored in real-life situations, the case study results in a rich and holistic account of a phenomenon. It offers insights and illuminates meanings that expand its readers' experiences. These insights can be construed as tentative hypotheses that help structure future research; hence, case study plays an important role in advancing a field's knowledge base. Because of its strengths, case study is a particularly appealing design for applied fields of study such as education, social work, administration, health, and so on. An applied field's processes, problems, and programs can be examined to bring about understanding that in turn can affect and perhaps even improve practice. Case study has proven particularly useful for studying educational innovations, evaluating programs, and informing policy.

Perhaps because a case study focuses on a single unit, a single instance, the issue of generalizability looms larger here than with other types of qualitative research. However, much can be learned from a particular case. Readers can learn vicariously from an encounter with the case through the researcher's narrative description. (Stake, 2005). The colorful description in a case study can create an image: "a vivid portrait of excellent teaching, for example--can become a prototype that can be used in the education of teachers or for the appraisal of teaching" (Eisner, 1991, p. 199). Further, Erickson (1986) argues that since the general lies in the particular, what we learn in a particular case can be transferred to similar situations. It is the reader, not the researcher, who determines what can apply to his or her context. Stake (2005, p. 455) explains how this knowledge transfer works: case researchers "will, like others, pass along to readers some of their personal meanings of events and relationships--and fail to pass along others. They know that the reader, too, will add and subtract, invent and shape--reconstructing the knowledge in ways that leave it...more likely to be personally useful."

The special features of case study research that provide the rationale for its selection also present certain limitations in it usage. Although rich, thick description and analysis of a phenomenon may be desired, a researcher may not have the time or money to devote to such an undertaking. And assuming time is available to produce a worthy case study, the product may be too lengthy, too detailed, or too involved for busy policy makers and practitioners to read and use. The amount of description, analysis, or summary material is up to the investigator. The researcher also must decide. "1. How much to make the report a story; 2. How much to compare with other cases; 3. How much to formalize generalizations or leave such generalizing to readers; 4. How much description of the researcher to include in the report; and, 5. Whether or not and how much to protect anonymity" (Stake, 2005, p. 460).

Qualitative case studies are limited, too, by the sensitivity and integrity of the investigator. The researcher is the primary instrument of data collection and analysis. This has its advantages. But training in observation and interviewing, though necessary, is not readily available to aspiring case study researchers. Nor are there guidelines in constructing the final report. The investigator is left to rely on his or her own instincts and abilities throughout most of this research effort.

A concern about case study research--and in particular case evaluation--is what Guba and Lincoln (1981) refer to as "unusual problems of ethics. An unethical case writer could so select from among available data that virtually anything he wished could be illustrated" (p. 378). Both the readers of case studies and the authors themselves need to be aware of biases that can affect the final product.

Further limitations involve the issues of reliability, validity, and generalizability. A Hamel (1993, p. 23) observes, "the case study has basically been faulted for its lack of representativeness...and its lack of rigor in the collection, construction, and analysis of the empirical materials that give rise to this study. This lack of rigor is linked to the problem of bias...introduced by the subjectivity of the researcher and others involved in the case. However, this argument against case study research misses the point of doing this type of research. In a recent presentation critiquing the new "gold standard" of randomized controlled trials in educational research, Shields (2007) argues for qualitative case studies: "The strength of qualitative approaches is that they account for and include difference--ideologically, epistemologically, methodologically--and most importantly, humanly. They do not attempt to eliminate what cannot be discounted. They do not attempt to simplify what cannot be simplified. Thus, it is precisely because case study includes paradoxes and acknowledges that there are no simple answers, that it can and should qualify as the gold standard" (p. 12). These issues, which are discussed more fully in  Chapter Nine, are the focus of much discussion in the literature on qualitative research generally.

In an interesting discussion of the value of case study research, Flyvbjerg (2006) sets up five "misunderstandings" about case study research, which he then dismantles, substituting a more accurate statement about the issue underlying each misunderstanding. These misunderstandings and their restatements are displayed in Table 3.1. The second misunderstanding, for example, "that one cannot generalize on the basis of a single case is usually considered to be devastating to the case study as a scientific method" (p.224). However, citing single cases, experiments, and experiences of Galileo, Newton, Einstein, Bohr, Darwin, Marx, and Freud, Flyvbjerg makes the point that both human and natural sciences can be advanced by a single case. He also argues that formal generalizations based on large samples are overrated in their contribution to scientific progress (for a discussion comparing sampling, representativeness, and generalizability in both quantitative and qualitative research, see Gobo, 2004).

TABLE 3.1.  FIVE MISUNDERSTANDINGS ABOUT CASE STUDY RESEARCH. ________________________________________________________________________________  Misunderstanding                                                           Restatement

1. General knowledge is more                            Universals can't be found in the

valuable than context-specific                         study of human affairs. Context-

knowledge.                                                         dependent knowledge is more valuable.

2. One can't generalize from                            Formal generalization is

a single case so a single case                             overvalued as a source of

doesn't add to scientific                                   scientific development; the

development.                                                     force of a single example is  underestimated

3. The case study is most useful                     The case study is useful for

in the first phase of a research                      both generating and testing of

process; used for generating                           hypotheses but is not limited to

hypotheses.                                                      these activities.

4. The case study confirms the                      There is no greater bias in

researcher's preconceived                             case study toward confirming

notions.                                                             preconceived notions than in

                                                                         other forms of research.

5. It is difficult to summarize                        Difficulty in summarizing case

case studies into general                                 studies is due to properties of the

propositions and theories.                                reality studied, not the research


Adapted form Flyvbjerg (2006), pp. 219-245).


Eisner, E.W. (1991). The enlightened eye: Qualitative inquiry and the enhancement of educational practice. Old Tappan, NJ: Macmillan.

Erickson, F. (1986). Qualitative methods in research on teaching. In M.C. Whittrock (Ed.), Handbook of research on teaching. (3rd ed.) (pp. 119-161). Old Tappan, NJ: Macmillan.

Flyvberg, B. (2006). Five misunderstanding about case-study research. Qualitative Inquiry, 12(2), 219-245.

Gobo, G. (2004). Sampling, representativeness and generalizability. In C. Seale, G. Gobo, J.F. Gubrium, & D. Silverman (Eds.) Qualitative research practice (pp. 435-456). London: Sage.

Guba, E., & Lincoln, Y. (1981). Effective evaluation. San Francisco: Jossey-Bass.

Hamel, J. (1993). Case Study methods. Qualitative Research Methods. Vol. 32. Thousand Oaks, CA: Sage.

Stake, R.E. (2005). Qualitative case studies. In N.K. Denzin & Y.S. Lincoln (Eds.) The Sage handbook of qualitative research (3rd ed.) (pp. 443-466). Thousand Oaks, CA: Sage.