The Case Study Method Of Scholarly Research Databases
Pragmatic Case Studies in Psychotherapy (PCSP) is a peer-reviewed, open-access journal and database. It provides innovative, quantitative and qualitative knowledge about psychotherapy process and outcome, for both researchers and practitioners.
GOALS OF THE JOURNAL
1) To generate a growing database of systematic, rigorous, and peer-reviewed therapy case studies across a variety of theoretical approaches. These cases can serve:
A) as a source of guidance on individual cases for practicing clinicians.
B) as a research base for qualitative and quantitative cross-case analysis by researchers and theorists. This research base can be employed (a) to derive and test theory-based hypotheses about therapy process and change mechanisms; (b) to develop pragmatic, evidence-based, "best practice" guidelines for addressing particular types of cases; (c) to explore effective ways to combine qualitative and quantitative information; and (d) to compare, contrast, and/or integrate different theoretical approaches as applied to the same clinical facts in individual cases.
C) as a way to enhance the knowledge value of cases employed in quantitatively oriented therapy research involving either groups of therapy patients (e.g., efficacy research) or single-case research designs.
D) as a resource in therapist training, for both students, academic educators, and supervisors.
2) To pilot-test the special advantages of online, case study journals in applied psychology generally by exemplifying in detail their ability to make large amounts of qualitative and quantitative, peer-reviewed information particularly timely, accessible, searchable, and pragmatically and theoretically valuable.
3) To act as a vehicle for progress in therapy case-study method through the process of example, critical dialogue, and cross-case analysis.
In recent years, there has been a vigorous, renewed interest by applied psychology researchers and scholars in case studies of therapy -- and other psychosocial interventions -- whose process and outcome are systematically described with "thick" qualitative detail (see sample list of references below). These authors have been drawn to the case study from a variety of theoretical and applied perspectives, such as cognitive-behaviorism, psychoanalysis, phenomenology, hermeneutics, humanistic psychology, life-history, personology, and program evaluation. In spite of this diversity, these authors have offered converging rationales for restoring the case study to its former prominence as a vehicle for systematically reporting clinical observations, exploring theory, and documenting advances in professional effectiveness.
Furthermore, these authors have developed a variety of similar guidelines for improving the reliability and generalizablity of the case study's content. For example, Elliott, Fischer, and Rennie (1999) recently reported the following guidelines that emerged from a consensus-seeking process among psychotherapy researchers: "owning one's perspective," involving specification of factors like the author's theoretical orientation, personal anticipations, and values, and the role these play in the research design and conceptual analysis; "situationing the sample," by describing relevant contextual data about the subjects involved; "providing reliability checks," by the use of multiple qualitative analysts and/or a research "auditor"; and "grounding in examples." This latter guideline is analogous to reporting significance tests in quantitative research, in the sense that both types of research practices form the empirical basis of the logic for supporting conclusions about the phenomena being studied.
We believe that the scholarship, sophistication, vitality, and pragmatic import of this recent work in case study method, along with the power of electronic publishing and searchable databases, permits the field of professional psychology to take a ma jor leap forward towards the integration of theory, research and practice. Our aim is to maintain the clinical richness and creativity of the case study method while generating a database that permits cross-case comparisons and more generalized rules of psychotherapeutic practice.
Drawing on major themes in the new applied case research models, Fishman (1999, 2000, 2001) uses the term "pragmatic case study" to refer to systematic, qualitative case studies that capture the logic, process, and outcome of professional practice. Such case studies also include, where feasible and theoretically consistent, intake and outcome data on standardized quantitative measures to place an individual patient in normative context.
Fishman has illustrated the nature and theoretical and practical value of pragmatic case studies through article series in two journals: one involving 8 cases studies in forensic psychology (Fishman & Delahunty, 2003, 2004); and one involving 6 case studies in program planning & evaluation, and community psychology (Fishman & Neigher, 2003, 2004). In each of these series, there are complementary articles on case study method and cross-case comparisons. Broad-based, pragmatic case studies as applied to the arena of psychotherapy are the guiding model for the cases in PCSP. The location of pragmatic case studies within the larger psychotherapy research field is described below.
From Single Case to Database in Psychotherapy Research
There is a very well established tradition in psychotherapy research for evaluating the comparative efficacy and effectiveness of different types of clinical interventions across groups of similar kinds of patients. (For examples of efficacy research, which is experimentally based, see Nathan & Gorman ; and for an example of effectiveness research, which is naturalistically-based, see Seligman .) The late Kenneth Howard and his colleagues (e.g., Howard, Moras, Brill, Zoran, Martinovitch, & Lutz, 1996;) call this tradition "treatment-focused" research, because it views the intervention model and procedures as the basic unit of analysis.
Howard and his colleagues have pioneered and developed an alternative, complementary approach, which they call "patient-focused research," because it views the individual case as the basic unit of analysis. More specifically, working in this paradigm, Howard et al. began by developing a common, omnibus, psychometrically established database of quantitative indicators normed on large numbers of patients and the general population, including a summary mental health index (MHI) score. For the patient sample, these measures were collected at intake, during therapy, and at follow-up. Then, by administering the same quantitative measures to a new client, a patient's psychometric intake profile could be matched to a group of similar patients in the database, and that group could be used to generate the expected course of therapy over time on the MHI score for that patient. The resultant feedback of how the patient is doing over time is of important practical use to the practitioner, supervisor, and case manager. At follow-up, patients' information goes into the database, adding to the power of the database, which can be employed for research trends across groups of patients. Howard's group has successfully pilot-tested their paradigm and continue to develop it (Grissom, Lyons, & Lutz, 2002).
One major goal of Pragmatic Case Studies in Psychotherapy (PCSP) is to expand the Howard model into the qualitative sphere, adding the capacity to look in process detail at cases that are normatively contextualized with quantitative measures like Howard's. In addition, PCSP is interested in other case study paradigms that focus on qualitative data per se. Specifically, while we expect many of the cases to be quantitatively contextualized, we anticipate other cases where quantitative measures are not feasible or where the author argues that quantitative data are not compatible w ith the theoretical model employed in the case. We believe that having such cases side by side with those that are quantitatively contextualized will stimulate constructive discussion and exploration of the potentials and limits of quantification in researching therapy.
In order to facilitate comparison among cases, it is important to strive for a common framework and structure embodied in common headings -- within each case. The editors of PCSP have chosen to begin their project with a framework developed by Donald Peterson (1997) titled "Disciplined Inquiry." This model has been chosen because it can accommodate (a) a wide array of different theoretical approaches, such as cognitive behavior therapy, psychodynamic therapy, humanistic therapy, and family systems; (b) the whole continuum defined by highly manualized treatment models at one end, highly individualized therapy at the other end, and some type of synthesis in the middle (e.g., Davison, 1998; Kendall, Chu, Gifford, Hayes, & Nauta, 1998; Persons, 2003); (c) and a variety of models of how the most effective practitioners in many fields actually function (e.g., the models of Schön's  "reflective practitioner" and Stricker & Trierweiler's  "local clinical scientist").
Briefly, Disciplined Inquiry requires the practitioner to lay out his or her "guiding conception" of therapy," as informed by published research and the practitioner's clinical experience. This guiding conception is then employed to create an individualized assessment, formulation, and treatment plan for the client. Interventions are next carried out -- with appropriate monitoring and feedback -- until termination, follow-up, and a concluding evaluation. (For a more detailed description of this Disciplined Inquiry, see Instructions for Authors.)
Clearly, the results of a single case study lack the ability for deductive generalization to other similar situations that is found in a group study. However, in line with the Howard et al. model, collections of case studies develop the capacity for inductive generalization to other, similar settings. This capacity can come about by organizing case studies of patients with similar target goals and similar intervention approaches into databases. For example, consider the application of cognitive behavior therapy to a phobia in a middle-class, professional Latina woman who has associated depressive symptoms, marital difficulties, and alcohol problems. Or consider family therapy with a poor, White teenager who is also a single mother of a child with attention deficit disorder. A write-up of either case is limited in terms of the number of case situations in the future to which it will apply. This limitation is due to large contextual differences that can occur between any one case and any other case that is randomly drawn out of a heterogeneous case pool.
However, as cases in the database grow, they begin to sample a wide variety of contextually different situations in which the target problem can occur and a wide variety of intervention approaches for that problem. Therefore, as the number of cases in the database rises substantially, the probability increases: (a) that there exist specific cases in the database that are pragmatically relevant to a new target case in terms of both the nature of the target problem and the intervention approach employed; and (b) that there are groups of cases that are contextually similar enough to inductively create general guidelines for working with and theoretically understanding such cases. (Note that this "case-based reasoning" [e.g., Fishman, 1999, 2003] is similar to the use of the Westlaw and Lexis databases in the legal profession.) To accomplish (a) and (b) involves a capacity for appropriate case-finding and for performing cross-case analyses where the units of study are in a large database with detailed qualitative data. These tasks seem only feasible with the online capacities of a journal like PCSP.
In sum, we have three broad goals for PCSP. First, the journal should be a vehicle for progress in therapy case study method through the process of example and critical dialogue. Second, the journal should be a vehicle for creating a growing database of systematic, rigorous, and peer-reviewed therapy case studies, which can serve as a systematic knowledge resource for practicing clinicians, for researchers and theorists, and for therapy educators and students. Finally, we view PCSP as an opportunity within the field of applied psychology generally to prove the special advantages of online journals in their ability to make large amounts of qualitative, peer-reviewed information particularly timely, accessible, searchable, and pragmatically and theoretically valuable.
SELECTED BIBLIOGRAPHY OF RECENT CASE STUDY RESEARCH AND THEORY
(* references specifically cited in the text)
Barlow, D.H. (Ed.). (2001). Clinical handbook of psychological disorders, third
edition: A step-by-step treatment manual. New York: Guilford Press.
Bromley, D.B. (1986). The case study method in psychology and related
disciplines. Chichester: John Wiley.
Clement, P.W. (1999). Outcomes & incomes: How to evaluate, improve, and
market your psychotherapy practice by measuring outcomes. New York:
COMPASSS Research Group (COMParative methods for the Advancement of
Systematic cross-case analysis and Small-n Studies). (2004). COMPASSS
is a research group bringing together scholars and practitioners who share
a common interest in theoretical, methodological and practical
advancements in a systematic comparative case approach to research
which stresses the use of a configurational logic, the existence of multiple
causality and the importance of a careful construction of research
populations. The web site of COMPASSS is http://www.compasss.org
*Davison, G.C. (1998). Being bolder with the Boulder model: The challenge of
education and training in empirically supported treatments. Journal of
Consulting and Clinical Psychology, 66, 163-167.
Davison, G.C. & Lazarus, A.A. (1994). Clinical innovation and evaluation:
Integrating practice with inquiry. Clinical Psychology: Science and Practice,
D'Zurilla, T. J., & Nezu, A. M. (1999). Problem-solving therapy: A social
competence approach to clinical intervention (2nd ed.). New York:
Edelson, M. (1988). Psychoanalysis: A theory in crisis. Chicago: University of
Chicago. Edwards, D. A. (1998). Types of case study work: A conceptual
framework for case-based research. Journal of Humanistic Psychology, 38,
*Elliott, R. (2001). Hermeneutic single-case efficacy design: An overview. In
K.J. Schneider, J.F.T. Bugenthal, and J.F. Pierson (Eds.), The handbook of
humanistic psychology, 315-326. Thousand Oaks, CA: Sage.
Elliott, R., Fischer, C.T., & Rennie, D.L. (1999). Evolving guidelines for
publication of qualitative research studies in psychology and related fields.
British Journal of Clinical Psychology, 38, 215-229.
*Fishman, D.B. (1999). From single case to database: Resolving the
"manualized treatment" versus "case formulation" dilemma. Panel discussion
presented at the annual conference of the Association for Advancement of
Behavior Therapy. Toronto, Canada.
*Fishman, D.B. (2000). Transcending the efficacy versus effectiveness
research debate: Proposal for a new, electronic "Journal of Pragmatic Case
Studies." Prevention & Treatment, 3, Article 8. Available on the World Wide
*Fishman, D.B. (2001). From single case to database: A new method for
enhancing psychotherapy, forensic, and other psychological practice.
Applied & Preventive Psychology, 10, 275-304.
*Fishman, D.B. (2003). Background on the "Psycholegal Lexis Proposal":
Exploring the potential of a systematic case study database in forensic
psychology. Psychology,Public Policy and Law, 9, 267-274. |
*Fishman, D.B. & Goodman-Delahunty, J. (Eds.). (2003, 2004). Pragmatic
psychology and the law, parts 1 and 2. Special Section of Psychology,
Public Policy, and Law,Volume 9, No. 3/4; and Volume 10, No. 1.
Fishman, D.B., & Neigher, W.D. (Eds.). (2003, 2004). Systematic case
studies in program evaluation, parts 1 and 2. Special section of Evaluation
and Program Planning, Volume 26, No. 4; and Volume 27, No. 1.
Fishman, D.B., & Messer, S.B. (2004). Case-based studies as a source of
unity in applied psychology. Chapter in R.J. Sternberg (Ed.), The Unification
of psychology: Prospect or pipedream?, 37-59. Washington, D.C.:
American Psychological Associaton.
Franklin, A. J. (1999). Invisibility syndrome and racial identity development in
psychotherapy and counseling African American men. Counseling
Freeman, A. (2002). Modifying therapeutic homework for patients with
personality disorders. Journal of Clinical Psychology, 58, 513-524
Goldfried, M. R. (1995). Toward a common language for case formulation.
Journal of Psychotherapy Integration, 5, 221-244.
Goldman, R. & Greenberg, L.S. (1995). A process-experiential approach to
case formulation. In Session: Psychotherapy in Practice, 1, 35-36, 42-51.
*Grissom, G.R., Lyons, J.S., & Lutz, W. (2002). Standing on the shoulders of
a giant: Development of an outcome management system based on the
dose model and phase model of psychotherapy. Psychotherapy Research,
Haaga, D.A.F. (1999). Major depression with anger attacks: The case of
Mary. Cognitive and Behavioral Practice, 6, 271-273.
Hayes, S.C., Barlow, D.H., & Nelson-Gray, R.O. (1999). The scientist
practitioner: Research and accountability in the age of managed care.
Boston: Allyn and Bacon.
Hersen, M. (2002). Rationale for Clinical Case Studies: An editorial. Clinical
Case Studies, 1, 3-5.
Hilliard, R.B. (1993). Single-case methodology in psychotherapy process and
outcome research. Journal of Consulting and Clinical Psychology, 61, 373-
Hoshmand, L.T. & Polkinghorne, D.E. (1992). Redefining the science-
practice relationship and professional training. American Psychologist, 47,
*Howard, K.I., Moras, K., Brill, P.L., Martinovich, Z., & Lutz, W. (1996).
Evaluation of psychotherapy: Efficacy, effectiveness, and patient
progress. American Psychologist, 51, 1059-1064.
Kanfer, F.H., & Schefft, B.K. (1988). Guiding the process of therapeutic
change. Champaign, Illinois: Research Press.
Kazdin, A.E. (1981). Drawing valid inferences from case studies. Journal of
Consulting and Clinical Psychology, 49, 183-192.
Kazdin, A. E. (1993). Evaluation in clinical practice: Clinically sensitive and
systematic methods of treatment delivery. Behavior Therapy, 24, 11-45.
*Kendall, P.C., Chu, B., Gifford, A., Hayes, C., & Nauta, M. (1998).
Breathing life into a manual: Flexibility and creativity with manual-based
treatments. Cognitive and Behavioral Practice, 5, 177-198.
Klumpner,G.H. & Frank, A. (1991). On methods of reporting clinical material.
Journal of the American Psychoanalytic Association, 39, 537-551.
Lazarus, A. A. (2002). .Client readiness for change, cultural concerns, and
risk taking: A multimodal case presentation. Clinical Case Studies, 1, 39-48.
Levine, M. (1980). Investigative reporting as a research method: An analysis
of Woodward and Bernstein's "All the President's Men." American
Psychologist, 35, 626-638.
Mahoney, M. J. (2003). The postmodern self in psychotherapy. Journal of
Cognitive Psychotherapy, 7, 241-250
McWilliams, N. (2004). Psychoanalytic psychotherapy: A practitioner's guide.
New York: Guilford.
Messer, S.B., & McCann, L. (in press). Research perspectives on the case
study: Single-case method. In J.S. Auerbach, K.N. Levy, & C.E. Schaffer.
Relatedness, self-definition, and mental representation: Essays in honor of
Sidney J. Blatt. New York: Routledge Press.
Miller, R.B. (2004). Facing human suffering: Psychology and psychotherapy
as moral engagement. Washington, DC: APA.
*Nathan, P.E., & Gorman, J.M. (Eds.). (2002). Aguide to treatments that
work, 2nd edition. New York: Oxford University Press.
Ogilvie, D.M. (2003). Fantasies of flight. New York: Oxford Press.
Persons, J.B. (1989). Cognitive therapy in practice: A case formulation
approach. New York: W.W. Norton.
*Persons, J.B. (2003, November 22). Empiricism, mechanism, and the practice
of cognitive-behavior therapy. Presidential address to the annual
convention of the Association for Advancement of Behavior Therapy.
*Peterson, D.R. (1997). Educating professional psychologists: History and
guiding conception. Washington, DC: American Psychological Association.
Runyan, W. M. (2003). From the study of lives and psychohistory to
historicizing psychology: A conceptual journey. Annual of Psychoanalysis,
Schneider, K.J. (1999). Multiple-case research: Bringing experience-near
closer. Journal of Clinical Psychology, 55, 1531-1540.
*Schön, D.A. (1983). The reflective practitioner. How professionals think in
action. New York: Basic Books.
Sechrest, L., Stewart, M., Stickle, T.R., & Sidani, S. (1996). Effective and
persuasive case studies. (Product # PN-20). Cambridge, MA: The
Evaluation Center @ HSRI.
*Seligman, M.E.P. (1995). The effectiveness of psychotherapy: The
Consumer Reports study. American Psychologist, 50, 965- 974.
Shapiro, M.B. (1961). The single case in fundamental psychological research.
British Journal of Medical Psychology, 34, 255-262.
Spence, D. P. (1993). Traditional case studies and prescriptions for improving
them. In N.E. Wilson (Ed.) Psychodynamic treatment research: A
handbook for clinical practice. New York : Basic Books.
Stake, R.E. (2000). Case studies. In N.K. Denzin & Y.S. Lincoln (Eds.).
Handbook of qualitative research, 2nd ed., 435-454. Thousand Oaks, CA:
Stiles, W.B., Shapiro, D.A., Harper, H., Morrison, L.A. (1995). Therapist
contributions to psychotherapeutic assimilation: An alternative to the drug
metaphor. British Journal of Medical Psychology, 68, 1-13.
*Stricker, G., & Trierweiler, S.J. (1995). The local clinical scientist: A bridge
between science and practice. American Psychologist, 50, 995-1002.
White, R. (1975). Lives in progress. New York: HBJ.
Yalom, I. & Elkins, G. (1977). Every day gets a little closer: A twice told
therapy. New York: Basic Books.
Yin, R.K. (2002). Case study research: Design and methods, 3rd ed.
Thousand Oaks: Sage.
What is a case study?
A case study is a research approach that is used to generate an in-depth, multi-faceted understanding of a complex issue in its real-life context. It is an established research design that is used extensively in a wide variety of disciplines, particularly in the social sciences. A case study can be defined in a variety of ways (Table 5), the central tenet being the need to explore an event or phenomenon in depth and in its natural context. It is for this reason sometimes referred to as a "naturalistic" design; this is in contrast to an "experimental" design (such as a randomised controlled trial) in which the investigator seeks to exert control over and manipulate the variable(s) of interest.
Stake's work has been particularly influential in defining the case study approach to scientific enquiry. He has helpfully characterised three main types of case study: intrinsic, instrumental and collective. An intrinsic case study is typically undertaken to learn about a unique phenomenon. The researcher should define the uniqueness of the phenomenon, which distinguishes it from all others. In contrast, the instrumental case study uses a particular case (some of which may be better than others) to gain a broader appreciation of an issue or phenomenon. The collective case study involves studying multiple cases simultaneously or sequentially in an attempt to generate a still broader appreciation of a particular issue.
These are however not necessarily mutually exclusive categories. In the first of our examples (Table 1), we undertook an intrinsic case study to investigate the issue of recruitment of minority ethnic people into the specific context of asthma research studies, but it developed into a instrumental case study through seeking to understand the issue of recruitment of these marginalised populations more generally, generating a number of the findings that are potentially transferable to other disease contexts. In contrast, the other three examples (see Tables 2, 3 and 4) employed collective case study designs to study the introduction of workforce reconfiguration in primary care, the implementation of electronic health records into hospitals, and to understand the ways in which healthcare students learn about patient safety considerations[4-6]. Although our study focusing on the introduction of General Practitioners with Specialist Interests (Table 2) was explicitly collective in design (four contrasting primary care organisations were studied), is was also instrumental in that this particular professional group was studied as an exemplar of the more general phenomenon of workforce redesign.
What are case studies used for?
According to Yin, case studies can be used to explain, describe or explore events or phenomena in the everyday contexts in which they occur. These can, for example, help to understand and explain causal links and pathways resulting from a new policy initiative or service development (see Tables 2 and 3, for example). In contrast to experimental designs, which seek to test a specific hypothesis through deliberately manipulating the environment (like, for example, in a randomised controlled trial giving a new drug to randomly selected individuals and then comparing outcomes with controls), the case study approach lends itself well to capturing information on more explanatory 'how', 'what' and 'why' questions, such as 'how is the intervention being implemented and received on the ground?'. The case study approach can offer additional insights into what gaps exist in its delivery or why one implementation strategy might be chosen over another. This in turn can help develop or refine theory, as shown in our study of the teaching of patient safety in undergraduate curricula (Table 4)[6,10]. Key questions to consider when selecting the most appropriate study design are whether it is desirable or indeed possible to undertake a formal experimental investigation in which individuals and/or organisations are allocated to an intervention or control arm? Or whether the wish is to obtain a more naturalistic understanding of an issue? The former is ideally studied using a controlled experimental design, whereas the latter is more appropriately studied using a case study design.
Case studies may be approached in different ways depending on the epistemological standpoint of the researcher, that is, whether they take a critical (questioning one's own and others' assumptions), interpretivist (trying to understand individual and shared social meanings) or positivist approach (orientating towards the criteria of natural sciences, such as focusing on generalisability considerations) (Table 6). Whilst such a schema can be conceptually helpful, it may be appropriate to draw on more than one approach in any case study, particularly in the context of conducting health services research. Doolin has, for example, noted that in the context of undertaking interpretative case studies, researchers can usefully draw on a critical, reflective perspective which seeks to take into account the wider social and political environment that has shaped the case.
Example of epistemological approaches that may be used in case study research
How are case studies conducted?
Here, we focus on the main stages of research activity when planning and undertaking a case study; the crucial stages are: defining the case; selecting the case(s); collecting and analysing the data; interpreting data; and reporting the findings.
Defining the case
Carefully formulated research question(s), informed by the existing literature and a prior appreciation of the theoretical issues and setting(s), are all important in appropriately and succinctly defining the case[8,12]. Crucially, each case should have a pre-defined boundary which clarifies the nature and time period covered by the case study (i.e. its scope, beginning and end), the relevant social group, organisation or geographical area of interest to the investigator, the types of evidence to be collected, and the priorities for data collection and analysis (see Table 7). A theory driven approach to defining the case may help generate knowledge that is potentially transferable to a range of clinical contexts and behaviours; using theory is also likely to result in a more informed appreciation of, for example, how and why interventions have succeeded or failed.
Example of a checklist for rating a case study proposal
For example, in our evaluation of the introduction of electronic health records in English hospitals (Table 3), we defined our cases as the NHS Trusts that were receiving the new technology. Our focus was on how the technology was being implemented. However, if the primary research interest had been on the social and organisational dimensions of implementation, we might have defined our case differently as a grouping of healthcare professionals (e.g. doctors and/or nurses). The precise beginning and end of the case may however prove difficult to define. Pursuing this same example, when does the process of implementation and adoption of an electronic health record system really begin or end? Such judgements will inevitably be influenced by a range of factors, including the research question, theory of interest, the scope and richness of the gathered data and the resources available to the research team.
Selecting the case(s)
The decision on how to select the case(s) to study is a very important one that merits some reflection. In an intrinsic case study, the case is selected on its own merits. The case is selected not because it is representative of other cases, but because of its uniqueness, which is of genuine interest to the researchers. This was, for example, the case in our study of the recruitment of minority ethnic participants into asthma research (Table 1) as our earlier work had demonstrated the marginalisation of minority ethnic people with asthma, despite evidence of disproportionate asthma morbidity[14,15]. In another example of an intrinsic case study, Hellstrom et al. studied an elderly married couple living with dementia to explore how dementia had impacted on their understanding of home, their everyday life and their relationships.
For an instrumental case study, selecting a "typical" case can work well. In contrast to the intrinsic case study, the particular case which is chosen is of less importance than selecting a case that allows the researcher to investigate an issue or phenomenon. For example, in order to gain an understanding of doctors' responses to health policy initiatives, Som undertook an instrumental case study interviewing clinicians who had a range of responsibilities for clinical governance in one NHS acute hospital trust. Sampling a "deviant" or "atypical" case may however prove even more informative, potentially enabling the researcher to identify causal processes, generate hypotheses and develop theory.
In collective or multiple case studies, a number of cases are carefully selected. This offers the advantage of allowing comparisons to be made across several cases and/or replication. Choosing a "typical" case may enable the findings to be generalised to theory (i.e. analytical generalisation) or to test theory by replicating the findings in a second or even a third case (i.e. replication logic). Yin suggests two or three literal replications (i.e. predicting similar results) if the theory is straightforward and five or more if the theory is more subtle. However, critics might argue that selecting 'cases' in this way is insufficiently reflexive and ill-suited to the complexities of contemporary healthcare organisations.
The selected case study site(s) should allow the research team access to the group of individuals, the organisation, the processes or whatever else constitutes the chosen unit of analysis for the study. Access is therefore a central consideration; the researcher needs to come to know the case study site(s) well and to work cooperatively with them. Selected cases need to be not only interesting but also hospitable to the inquiry  if they are to be informative and answer the research question(s). Case study sites may also be pre-selected for the researcher, with decisions being influenced by key stakeholders. For example, our selection of case study sites in the evaluation of the implementation and adoption of electronic health record systems (see Table 3) was heavily influenced by NHS Connecting for Health, the government agency that was responsible for overseeing the National Programme for Information Technology (NPfIT). This prominent stakeholder had already selected the NHS sites (through a competitive bidding process) to be early adopters of the electronic health record systems and had negotiated contracts that detailed the deployment timelines.
It is also important to consider in advance the likely burden and risks associated with participation for those who (or the site(s) which) comprise the case study. Of particular importance is the obligation for the researcher to think through the ethical implications of the study (e.g. the risk of inadvertently breaching anonymity or confidentiality) and to ensure that potential participants/participating sites are provided with sufficient information to make an informed choice about joining the study. The outcome of providing this information might be that the emotive burden associated with participation, or the organisational disruption associated with supporting the fieldwork, is considered so high that the individuals or sites decide against participation.
In our example of evaluating implementations of electronic health record systems, given the restricted number of early adopter sites available to us, we sought purposively to select a diverse range of implementation cases among those that were available. We chose a mixture of teaching, non-teaching and Foundation Trust hospitals, and examples of each of the three electronic health record systems procured centrally by the NPfIT. At one recruited site, it quickly became apparent that access was problematic because of competing demands on that organisation. Recognising the importance of full access and co-operative working for generating rich data, the research team decided not to pursue work at that site and instead to focus on other recruited sites.
Collecting the data
In order to develop a thorough understanding of the case, the case study approach usually involves the collection of multiple sources of evidence, using a range of quantitative (e.g. questionnaires, audits and analysis of routinely collected healthcare data) and more commonly qualitative techniques (e.g. interviews, focus groups and observations). The use of multiple sources of data (data triangulation) has been advocated as a way of increasing the internal validity of a study (i.e. the extent to which the method is appropriate to answer the research question)[8,18-21]. An underlying assumption is that data collected in different ways should lead to similar conclusions, and approaching the same issue from different angles can help develop a holistic picture of the phenomenon (Table 2).
Brazier and colleagues used a mixed-methods case study approach to investigate the impact of a cancer care programme. Here, quantitative measures were collected with questionnaires before, and five months after, the start of the intervention which did not yield any statistically significant results. Qualitative interviews with patients however helped provide an insight into potentially beneficial process-related aspects of the programme, such as greater, perceived patient involvement in care. The authors reported how this case study approach provided a number of contextual factors likely to influence the effectiveness of the intervention and which were not likely to have been obtained from quantitative methods alone.
In collective or multiple case studies, data collection needs to be flexible enough to allow a detailed description of each individual case to be developed (e.g. the nature of different cancer care programmes), before considering the emerging similarities and differences in cross-case comparisons (e.g. to explore why one programme is more effective than another). It is important that data sources from different cases are, where possible, broadly comparable for this purpose even though they may vary in nature and depth.
Analysing, interpreting and reporting case studies
Making sense and offering a coherent interpretation of the typically disparate sources of data (whether qualitative alone or together with quantitative) is far from straightforward. Repeated reviewing and sorting of the voluminous and detail-rich data are integral to the process of analysis. In collective case studies, it is helpful to analyse data relating to the individual component cases first, before making comparisons across cases. Attention needs to be paid to variations within each case and, where relevant, the relationship between different causes, effects and outcomes. Data will need to be organised and coded to allow the key issues, both derived from the literature and emerging from the dataset, to be easily retrieved at a later stage. An initial coding frame can help capture these issues and can be applied systematically to the whole dataset with the aid of a qualitative data analysis software package.
The Framework approach is a practical approach, comprising of five stages (familiarisation; identifying a thematic framework; indexing; charting; mapping and interpretation), to managing and analysing large datasets particularly if time is limited, as was the case in our study of recruitment of South Asians into asthma research (Table 1)[3,24]. Theoretical frameworks may also play an important role in integrating different sources of data and examining emerging themes. For example, we drew on a socio-technical framework to help explain the connections between different elements - technology; people; and the organisational settings within which they worked - in our study of the introduction of electronic health record systems (Table 3). Our study of patient safety in undergraduate curricula drew on an evaluation-based approach to design and analysis, which emphasised the importance of the academic, organisational and practice contexts through which students learn (Table 4).
Case study findings can have implications both for theory development and theory testing. They may establish, strengthen or weaken historical explanations of a case and, in certain circumstances, allow theoretical (as opposed to statistical) generalisation beyond the particular cases studied. These theoretical lenses should not, however, constitute a strait-jacket and the cases should not be "forced to fit" the particular theoretical framework that is being employed.
When reporting findings, it is important to provide the reader with enough contextual information to understand the processes that were followed and how the conclusions were reached. In a collective case study, researchers may choose to present the findings from individual cases separately before amalgamating across cases. Care must be taken to ensure the anonymity of both case sites and individual participants (if agreed in advance) by allocating appropriate codes or withholding descriptors. In the example given in Table 3, we decided against providing detailed information on the NHS sites and individual participants in order to avoid the risk of inadvertent disclosure of identities[5,25].
What are the potential pitfalls and how can these be avoided?
The case study approach is, as with all research, not without its limitations. When investigating the formal and informal ways undergraduate students learn about patient safety (Table 4), for example, we rapidly accumulated a large quantity of data. The volume of data, together with the time restrictions in place, impacted on the depth of analysis that was possible within the available resources. This highlights a more general point of the importance of avoiding the temptation to collect as much data as possible; adequate time also needs to be set aside for data analysis and interpretation of what are often highly complex datasets.
Case study research has sometimes been criticised for lacking scientific rigour and providing little basis for generalisation (i.e. producing findings that may be transferable to other settings). There are several ways to address these concerns, including: the use of theoretical sampling (i.e. drawing on a particular conceptual framework); respondent validation (i.e. participants checking emerging findings and the researcher's interpretation, and providing an opinion as to whether they feel these are accurate); and transparency throughout the research process (see Table 8)[8,18-21,23,26]. Transparency can be achieved by describing in detail the steps involved in case selection, data collection, the reasons for the particular methods chosen, and the researcher's background and level of involvement (i.e. being explicit about how the researcher has influenced data collection and interpretation). Seeking potential, alternative explanations, and being explicit about how interpretations and conclusions were reached, help readers to judge the trustworthiness of the case study report. Stake provides a critique checklist for a case study report (Table 9).
Potential pitfalls and mitigating actions when undertaking case study research
Stake's checklist for assessing the quality of a case study report