Case study
A case study is an intensive analysis of an individual unit (e.g., a person, group, or event) stressing developmental factors in relation to context. The case study is common in social sciences
Social sciences
Social science is the field of study concerned with society. "Social science" is commonly used as an umbrella term to refer to a plurality of fields outside of the natural sciences usually exclusive of the administrative or managerial sciences...

 and life sciences
Life sciences
The life sciences comprise the fields of science that involve the scientific study of living organisms, like plants, animals, and human beings. While biology remains the centerpiece of the life sciences, technological advances in molecular biology and biotechnology have led to a burgeoning of...

. Case studies may be descriptive or explanatory. The latter type is used to explore causation in order to find underlying principles. They may be prospective
Prospective cohort study
A prospective cohort study is a cohort study that follows over time a group of similar individuals who differ with respect to certain factors under study, to determine how these factors affect rates of a certain outcome...

, in which criteria are established and cases fitting the criteria are included as they become available, or retrospective
Retrospective generally means to take a look back at events that already have taken place. For example, the term is used in medicine, describing a look back at a patient's medical history or lifestyle.-Music:...

, in which criteria are established for selecting cases from historical records for inclusion in the study.

Thomas offers the following definition of case study: "Case studies are analyses of persons, events, decisions, periods, projects, policies, institutions, or other systems that are studied holistically by one or more methods. The case that is the subject of the inquiry will be an instance of a class of phenomena that provides an analytical frame — an object — within which the study is conducted and which the case illuminates and explicates."

Rather than using samples and following a rigid protocol (strict set of rules) to examine limited number of variables, case study methods involve an in-depth, longitudinal (over a long period of time) examination of a single instance or event: a case. They provide a systematic way of looking at events, collecting data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

, analyzing information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...

, 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.

Another suggestion is 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. Case studies should not be confused with qualitative research
Qualitative research
Qualitative research is a method of inquiry employed in many different academic disciplines, traditionally in the social sciences, but also in market research and further contexts. Qualitative researchers aim to gather an in-depth understanding of human behavior and the reasons that govern such...

 and they can be based on any mix of quantitative and qualitative evidence. Single-subject research
Single-subject research
Single-subject research is a group of research methods that are used extensively in the experimental analysis of behavior and applied behavior analysis with both human and non-human participants. Four principal methods in this type of research are: changing criterion, reversal , alternating...

 provides the statistical framework for making inferences from quantitative case-study data. This is also supported and well-formulated in (Lamnek, 2005): "The case study is a research approach, situated between concrete data taking techniques and methodologic paradigms."

The case study is sometimes mistaken for the case method
Case method
The case method is a teaching approach that consists in presenting the students with a case, putting them in the role of a decision maker facing a problem...

, but the two are not the same.

Case selection and structure of the case study

An average, or typical, case is often not the richest in information. In clarifying lines of history and causation it is more useful to select subjects that offer an interesting, unusual or particularly revealing set of circumstances. A case selection that is based on representativeness will seldom be able to produce these kinds of insights. When selecting a subject for a case study, researchers will therefore use information-oriented sampling, as opposed to random sampling. Outlier
In statistics, an outlier is an observation that is numerically distant from the rest of the data. Grubbs defined an outlier as: An outlying observation, or outlier, is one that appears to deviate markedly from other members of the sample in which it occurs....

 cases (that is, those which are extreme, deviant or atypical) reveal more information than the putatively representative case. Alternatively, a case may be selected as a key case, chosen because of the inherent interest of the case or the circumstances surrounding it. Or it may be chosen because of researchers' in-depth local knowledge; where researchers have this local knowledge they are in a position to “soak and poke” as Fenno puts it, and thereby to offer reasoned lines of explanation based on this rich knowledge of setting and circumstances.

Three types of cases may thus be distinguished:
  1. Key cases
  2. Outlier cases
  3. Local knowledge cases

Whatever the frame of reference for the choice of the subject of the case study (key, outlier, local knowledge), there is a distinction to be made between the subject and the object of the case study. The subject is the “practical, historical unity” through which the theoretical focus of the study is being viewed. The object is that theoretical focus – the analytical frame. Thus, for example, if a researcher were interested in US resistance to communist expansion as a theoretical focus, then the Korean War might be taken to be the subject, the lens, the case study through which the theoretical focus, the object, could be viewed and explicated.

Beyond decisions about case selection and the subject and object of the study, decisions need to be made about purpose, approach and process in the case study. Thomas thus proposes a typology for the case study wherein purposes are first identified (evaluative or exploratory), then approaches are delineated (theory-testing, theory-building or illustrative), then processes are decided upon, with a principal choice being between whether the study is to be single or multiple, and choices also about whether the study is to be retrospective, snapshot or diachronic, and whether it is nested, parallel or sequential. It is thus possible to take many routes through this typology, with, for example, an exploratory, theory-building, multiple, nested study, or an evaluative, theory-testing, single, retrospective study. The typology thus offers many permutations for case study structure.

For more on case selection, see

Generalizing from case studies

A critical case can be defined as having strategic importance in relation to the general problem. A critical case allows the following type of generalization, ‘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.’

The case study is also effective for generalizing using the type of test that Karl Popper
Karl Popper
Sir Karl Raimund Popper, CH FRS FBA was an Austro-British philosopher and a professor at the London School of Economics...

 called falsification
Falsification may refer to:* The act of disproving a proposition, hypothesis, or theory: see Falsifiability* Mathematical proof* Falsified evidence...

, which forms part of critical reflexivity. 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
Black Swan
The Black Swan is a large waterbird, a species of swan, which breeds mainly in the southeast and southwest regions of Australia. The species was hunted to extinction in New Zealand, but later reintroduced. Within Australia they are nomadic, with erratic migration patterns dependent upon climatic...

 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."

Galileo Galilei
Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...

’s rejection of Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

’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. 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.(Flyvbjerg, 2006, p. 225-6)

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. However it was Galileo's view that was the subject of doubt as it was not reasonable enough to be the Aristotelian view. By selecting cases strategically in this manner one may arrive at case studies that allow generalization.(Flyvbjerg, 2006, p. 225-6) For more on generalizing from case studies, see hiya

The case study paradox

Case studies have existed as long as recorded history. Much of what is known about the empirical world has been produced by case study research, and many of the classics in a long range of disciplines are case studies, including in psychology, sociology, anthropology, history, education, economics, political science, management, geography, biology, and medical science. Half of all articles in the top political science journals use case studies, for instance. But there is a paradox here, as argued by Oxford professor Bent Flyvbjerg. At the same time that case studies are extensively used and have produced canonical works, one may observe that the case study is generally held in low regard, or is simply ignored, within the academy. Statistics on courses offered in universities confirm this. It has been argued that the case study paradox exists because the case study is widely misunderstood as a research method. Flyvbjerg argues that by clearing the misunderstandings about the case study, the case study paradox may be resolved

The debate regarding case study's value as a research method

Flyvbjerg (2006) identified five statements regarding the limitations of case study as a research:
  1. General, theoretical knowledge is more valuable than concrete, practical knowledge.
  2. One cannot generalize on the basis of an individual case and, therefore, the case study cannot contribute to scientific development.
  3. The case study is most useful for generating hypotheses, whereas other methods are more suitable for hypotheses testing and theory building.
  4. The case study contains a bias toward verification, i.e., a tendency to confirm the researcher’s preconceived notions.
  5. It is often difficult to summarize and develop general propositions and theories on the basis of specific case studies.

These statements can be said to represent the cautionary view of case studies in conventional philosophy of science. Flyvbjerg (2006) argued that these statements are too categorical, and argued for the value of phenomenological insights gleamed by closely examining contextual "expert knowledge".

History of the case study

It is generally believed that the case-study method was first introduced into social science by Frederic Le Play in 1829 as a handmaiden to statistics in his studies of family budgets. (Les Ouvriers Europeens (2nd edition, 1879).

The use of case studies for the creation of new theory in social sciences has been further developed by the sociologists Barney Glaser
Barney Glaser
Barney G. Glaser is an American sociologist and one of the founders of the grounded theory methodology.Glaser was born in San Francisco, California, and lives in Mill Valley. He received his BA degree at Stanford in 1952. He pursued academic studies at the University of Paris where he studied...

 and Anselm Strauss
Anselm Strauss
Anselm Leonard Strauss was an American sociologist internationally known as a medical sociologist and as the developer of grounded theory, an innovative method of qualitative analysis widely used in sociology, nursing, education, social work, and...

 who presented their research method, Grounded theory
Grounded theory
Grounded theory is a systematic methodology in the social sciences involving the generation of theory from data. It is mainly used in qualitative research, but is also applicable to quantitative data....

, in 1967.

The popularity of case studies in testing hypotheses 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.

Case studies have also been used as a teaching method and as part of professional development, especially in business and legal education. The problem-based learning
Problem-based learning
Problem-based learning is a student-centered pedagogy in which students learn about a subject in the context of complex, multifaceted, and realistic problems...

 (PBL) movement is such an example. When used in (non-business) education and professional development, case studies are often referred to as critical incidents.

When the Harvard Business School
Harvard Business School
Harvard Business School is the graduate business school of Harvard University in Boston, Massachusetts, United States and is widely recognized as one of the top business schools in the world. The school offers the world's largest full-time MBA program, doctoral programs, and many executive...

 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 practitioners of business and to write detailed accounts of what these managers were doing. Cases are generally written by business school
Business school
A business school is a university-level institution that confers degrees in Business Administration. It teaches topics such as accounting, administration, economics, entrepreneurship, finance, information systems, marketing, organizational behavior, public relations, strategy, human resource...

 faculty with particular learning objectives in mind and are refined in the classroom before publication. Additional relevant documentation (such as financial statements, time-lines, and short biographies, often referred to in the case as "exhibits"), multimedia supplements (such as video-recordings of interviews with the case protagonist), and a carefully crafted teaching note often accompany cases.

See also

  • Casebook method
    Casebook method
    The casebook method, also known as the case method, is the primary method of teaching law in law schools in the United States. It was pioneered at Harvard Law School by Christopher Columbus Langdell...

  • Case method
    Case method
    The case method is a teaching approach that consists in presenting the students with a case, putting them in the role of a decision maker facing a problem...

  • Case study in psychology
    Case study in psychology
    Case study in psychology refers to the use of a descriptive research approach to obtain an in-depth analysis of a person, group, or phenomenon. A variety of techniques may be employed including personal interviews, direct-observation, psychometric tests, and archival records...

  • Phronetic social science
    Phronetic social science
    Phronetic social science is an approach to the study of social – including political and economic – phenomena based on a contemporary interpretation of the Aristotelian concept phronesis, variously translated as practical judgment, common sense, or prudence. Phronesis is the intellectual virtue...

  • Case competition
    Case competition
    In a case competition, participants compete for the best solution to a business case study under time pressure. Most often it is a competition at university level, but on occasions also held at other levels. The case competition is an event in which business teams deliver business presentations,...

Useful Sources

  • Baxter, P and Jack, S. (2008) Qualitative Case Study Methodology: Study design and implementation for novice researchers, in The Qualitative Report, 13(4): 544-559. Available from
  • Dul, J. and Hak, T (2008). Case Study Methodology in Business Research. Oxford: Butterworth-Heinemann. ISBN 978-0-7506-8196-4.
  • Eisenhardt, K. M. (1989). Building theories from case study research. The Academy of Management Review, 14 (4), Oct, 532-550.
  • Flyvbjerg, Bent, Making Social Science Matter: Why Social Inquiry Fails and How It Can Succeed Again (Cambridge: Cambridge University Press
    Cambridge University Press
    Cambridge University Press is the publishing business of the University of Cambridge. Granted letters patent by Henry VIII in 1534, it is the world's oldest publishing house, and the second largest university press in the world...

    , 2001). ISBN 052177568X
  • Flyvbjerg, Bent. (2006). Five Misunderstandings About Case-Study Research, in Qualitative Inquiry, 12(2): 219-245. Available:
  • Flyvbjerg, Bent. (2011) "Case Study," in Norman K. Denzin and Yvonna S. Lincoln, eds., The Sage Handbook of Qualitative Research, 4th Edition. Thousand Oaks, CA: Sage, pp. 301-316.
  • George, Alexander L. and Bennett,Andrew. (2005). Case studies and theory development in the social sciences. London, MIT Press 2005. ISBN 0-262-57222-2
  • Gerring, John. (2005) Case Study Research. New York: Cambridge University Press. ISBN 978-0-521-67656-4
  • Hancké, Bob. (2009) Intelligent Research Design. A guide for beginning researchers in the social sciences. Oxford University Press.
  • Lijphart, Arend.(1971)Comparative Politics and the Comparative Method,in The American Political Science Review, 65(3): 682-693. Available from
  • Ragin, Charles C. and Becker, Howard S. eds. (1992) What is a Case? Exploring the Foundations of Social Inquiry Cambridge: Cambridge University Press. ISBN 0521421888
  • Scholz, Roland W. and Tietje, Olaf. (2002) Embedded Case Study Methods. Integrating Quantitative and Qualitative Knowledge. Sage Publications. Thousand Oaks 2002, Sage. ISBN 0761919465 ,9337270973
  • Straits, Bruce C. and Singleton, Royce A. (2004) Approaches to Social Research, 4th ed.Oxford University Press
    Oxford University Press
    Oxford University Press is the largest university press in the world. It is a department of the University of Oxford and is governed by a group of 15 academics appointed by the Vice-Chancellor known as the Delegates of the Press. They are headed by the Secretary to the Delegates, who serves as...

    . ISBN 0195147944 Available from:
  • Thomas, Gary (2011) How to do your Case Study: A Guide for Students and Researchers. Thousand Oaks: Sage.

External links

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