Case study

A case study is an in-depth investigation of a single case or instance in a real context -- a single person, patient, group, event, community, organization, or business. It allows for detailed exploration of complex events or phenomena. The data involved are often gathered from observations, interviews, or other methods. Case studies have been used in clinical medicine and clinical psychology, e.g., detailed case studies of patients, focusing on a particular illness or a patient's experience. In business, one can examine a particular company's strategy and market performance. In political science and policy studies, one can investigate the complexities of a political event, campaign, or events leading to a major historical event or action (e.g., a war, a major political reform). In education, one can examine educational and learning experiences in detail from the viewpoint of student or teachers.

Case studies can focus on one individual, or a small group of individuals. It is a qualitative research method, as it does not involve a controlled comparison of carefully selected groups, and thus, is not based on the scientific method and does not involve statistical analysis. As such, its advantage is in considering a larger number of factors that might be involved. It can be especially advantageous for exploratory study of a complex or poorly understood phenomenon, and for generating a hypothesis or model about such a phenomenon that can be followed up with other research methods.

1 Study design

Qualitative studies usually begin with a research question (unlike scientific and data-heavy quantitative research studies, which begin with a specific hypothesis that is to be proved or disproved). A research question can be more open-ended and exploratory, such as:

• How do Mexican immigrant children adapt to an English-only grade school in a small city?
• How do COVID-19 patients handle the unique psychological challenges of being quarantined at home?
• How did AMD (the CPU manufacturer) make such a strong rebound after years of poor performance?
• What are the prospects for a company's success in a new market, based on their past performance and their current business practices?

A case study may simply be conducted to understand and analyze a complex situation, e.g., the growth, success, and/or failure of a company, or students' experiences in a particular learning environment. It might be used to generate a new model or hypothesis, which can lead to further research with different research methods, as in clinical case studies. It might be used for identifying anomalies that do not fit existing theories, in order to refine or challenge an existing theory (e.g., in applied linguistics research).

In clinical and educational case studies, case selection is one of the first considerations, as a study subject (the participant) must be identified who is a representative or typical sample for what one wishes to study; otherwise, if it is an atypical or outlier case, the study results will be of limited value. Sometimes this can be overcome with a larger case study of several participants, as in some educational linguistics studies.

Another consideration is the depth or "thickness" of the data, or how much detail the researcher wants to include. For example, this can range to a simple description in a few paragraphs of a language learner's experiences in a particular language course, to a very detailed biographical profile of the subject's language learning experience, his/her experiences throughout a course, multiple interviews with the subject over a semester, and observational data of the subject's classroom activities.

The data can be interpreted within an existing theory, model or framework for analysis, as well as the researcher's own professional experience. Additionally, interview data may be transcribed and coded (e.g., different aspects of the data are classified into different categories) and studied using other qualitative methods. The data may be analyzed without an existing theoretical framework, e.g., when a researcher conducts exploratory research on a new topic, and uses a case study as an exploratory research method to then develop a hypothesis based on the case study results. This hypothesis can then be developed and tasted in later research.

2 Use in different fields

Case studies have been famously used in psychology and psychoanalysis. Most notably, Sigmund Freud used case studies by interviewing his patients and making inferences from his interviews and observations. His case study data led to the development of his theories of psychology and psychoanalysis. This, however, shows the limitations of case studies, as many aspects of his theories were rejected by the psychological and scientific community. A case study can lead to good hypotheses and theories, or to flawed hypotheses and theories. A hypothesis or theory needs to be subjected to rigorous scientific testing in order to validate it. If theories are developed solely on case studies are not tested with other research methods, and are accepted simply on pragmatic grounds -- they seem to work -- this can lead to acceptance of a flawed theory. For clinical and educational fields, a flawed theory can have negative effects.

2.1 Business case studies

In business fields, case studies are not usually used for exploratory purposes, or to develop new theories. They are usually used simply to describe and analyze the history of a company or organization. Many times, business case studies are less formal, as they do not rely heavily on a theory or model to explain the data, though some business case studies do make use of a model or theory that the researchers have found useful. Occasionally, case study research may be used to develop a new model for analyzing business cases. Most business case studies, however, are more semi-formal, as they are mainly used to gain a practical understanding of a company or organization. The research questions might be focused on topics such as:

• Reasons for a company's success
• Reasons for a company's poor performance
• Reasons for a company's failure
• Likely prospects for a company based on its past performance, and based on its current leadership and performance