Case studies

Psychology AS · Research methodology. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

A case study is a detailed investigation of one participant or one unit. The unit can be a single person, a family, a school or an organisation. The aim is depth, not a large sample.

A case study is not one technique. The researcher gathers data in several ways, such as interviews, observations, psychological tests and records, often over a long time. Using several methods together is called triangulation, and it lets findings be checked against each other.

Case studies are most useful for rare or unusual cases that could not be created in an experiment. The cost is that one case may not tell us about other people.

Rules to remember

Case study: one individual or unit studied in detail, usually with several methods.
Data are mostly qualitative and rich, but can include quantitative data such as test scores.
Strength: depth and detail, high validity, and the chance to study rare cases that would be impossible or unethical to create.
Strength: can suggest new ideas for later research.
Weakness: findings cannot be generalised, because one case may be unique.
Weakness: hard to replicate, and the researcher may become close to the participant and lose objectivity (researcher bias).
Ethics: confidentiality is hard to protect when a case is unusual, and long, close study can be intrusive.

Common mistake

Students describe a case study as 'an interview with one person'. It is an in-depth study of one case that normally combines several techniques, and the case can be a group or an organisation.

Worked example

A researcher studies one small village school with unusually high exam results. For a year she interviews teachers, observes lessons and analyses test scores. Is this a case study, and can she conclude that her findings will work in all schools?

One school is a single unit, studied in depth over time, so this is a case study.
She uses interviews, observations and scores, so several methods are combined.
The school may be unusual in its size, pupils or teachers.
One unusual case cannot represent every school, so the results cannot be generalised.

Answer: Yes, it is a case study of one unit; no, the findings cannot be generalised to all schools, though they can suggest ideas to test in further research.

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