Case studies are in-depth investigations of a single person, group, event or community. Typically data are gathered from a variety of sources and by using several different methods (e.g. observations & interviews). The case study research method originated in clinical medicine (the case history, i.e. the patient’s personal history - idiographic method).
The case study method often involves simply observing what happens to, or reconstructing ‘the case history’ of a single participant or group of individuals (such as a school class or a specific social group), i.e. the idiographic approach. Case studies allow a researcher to investigate a topic in far more detail than might be possible if they were trying to deal with a large number of research participants (nomothetic approach) with the aim of ‘averaging’.
The case study is not itself a research method, but researchers select methods of data collection and analysis that will generate material suitable for case studies such as qualitative techniques (semi-structured interviews, participant observation, diaries), personal notes (e.g. letters, photographs, notes) or official document (e.g. case notes, clinical notes, appraisal reports). The data collected can be analysed using different theories (e.g. grounded theory, interpretative phenomenological analysis, text interpretation (e.g. thematic coding) etc. All the approaches mentioned here use preconceived categories in the analysis and they are ideographic in their approach, i.e. they focus on the individual case without reference to a comparison group.
Case studies are widely used in psychology and amongst the best known were the ones carried out by Sigmund Freud. He conducted very detailed investigations into the private lives of his patients in an attempt to both understand and help them overcome their illnesses. Freud's most famours case studies include Little Hans and The Rat Man. Even today case histories are one of the main methods of investigation in abnormal psychology and psychiatry. For students of these disciplines they can give a vivid insight into what those who suffer from mental illness often have to endure.
Case studies are often conducted in clinical medicine and involve collecting and reporting descriptive information about a particular person or specific environment, such as a school. In psychology, case studies are often confined to the study of a particular individual. The information is mainly biographical and relates to events in the individual's past (i.e. retrospective), as well as to significant events which are currently occurring in his or her everyday life. In order to produce a fairly detailed and comprehensive profile of the person, the psychologist may use various types of accessible data, such as medical records, employer's reports, school reports or psychological test results. The interview is also an extremely effective procedure for obtaining information about an individual, and it may be used to collect comments from the person's friends, parents, employer, workmates and others who have a good knowledge of the person, as well as to obtain facts from the person him or herself.
This makes it clear that the case study is a method that should only be used by a psychologist, therapist or psychiatrist, i.e. someone with a professional qualification. There is an ethical issue of competence. Only someone qualified to diagnose and treat a person can conduct a formal case study relating to atypical (i.e. abnormal) behaviour or atypical development. The procedure used in a case study means that the researcher provides a description of the behaviour. This comes from interviews and other sources, such as observation. The client also reports detail of events from his or her point of view. The researcher then writes up the information from both sources above as the case study, and interprets the information. Interpreting the information means the researcher decides what to include or leave out. A good case study should always make clear which information is factual description and which is inference or the opinion of the researcher.
• Provides detailed (rich qualitative) information
• Provides insight for further research
• Permitting investigation of otherwise impractical (or unethical) situations
Case studies give psychological researchers the possibility to investigate cases, which could not possibly be engineered in research laboratories. For example, the Money Case Study.
Case studies are often used in exploratory research. They can help us generate new ideas (that might be tested by other methods). They are an important way of illustrating theories and can help show how different aspects of a person's life are related to each other. The method is therefore important for psychologists who adopt a holistic point of view (i.e. humanistic psychologists).
• Can’t generalise the results to the wider population
• Researchers own subjective feeling may influence the case study (researcher bias)
• Difficult to replicate
• Time consuming
Because a case study deals with only one person/event/group we can never be sure whether conclusions drawn from this particular case apply elsewhere. The results of the study are not generaliseable because we can never know whether the case we have investigated is representative of the wider body of "similar" instances
Because they are based on the analysis of qualitative (i.e. descriptive) data a lot depends on the interpretation the psychologist places on the information she has acquired. This means that there is a lot of scope for observer bias and it could be that the subjective opinions of the psychologist intrude in the assessment of what the data means. For example, Freud has been criticised for producing case studies in which the information was sometimes distorted to fit the particular theories about behaviour (e.g. Little Hans). This is also true of Money’s interpretation of the Bruce/Brenda case study when he ignored evidence that went against his theory.