Case study: a single case, in depth
A case study is a detailed, in-depth investigation of a single case — one individual, small group, institution or event — usually over a long period.
Two parts must both be present: it is in-depth (rich information gathered), and it is about a single case, not a large sample.
It usually combines several techniques — interviews, observations, tests, secondary data — often longitudinally, producing mostly qualitative data.
Strengths: depth, rare cases, realism
Learn the strengths as a chain — the depth makes the others possible.
Weaknesses: hard to generalise, subjective
The strengths come at a cost; the weaknesses show what a case study is not good for.
It suits a rare case in depth, not a general law.
Drawn from real examiner reports.
"In-depth" alone is not a definition
Asked what a case study is, many write "an in-depth investigation". Alone this earns nothing — several methods are in-depth. The defining feature is that it studies a single case (one individual, group, institution or event) in depth.
Defining it only as "using several methods" also fails — that describes triangulation. Always anchor to the single case.
That "an in-depth investigation" alone fails as a definition of a case study because it fits other methods, and that "uses a number of different methods" describes triangulation rather than a case study, are both recorded in the June 2024 Paper 2 Q5a examiner report.
Naming a weakness, not explaining it
"Explain a strength/weakness" is not "describe" one. Naming a feature earns little; marks come from why it matters to the study.
The consequence holds the mark — for strengths too: "it is detailed" needs why depth gives a fuller picture.
June 2023 and June 2024 Paper 2 Summaries state that answers to explain-a-strength or explain-a-weakness questions must not only describe the feature, and identification without justification is recorded in June 2024 Paper 1 Q11b and Q15b.
Use the case study, not the theory
Asked to use the case study to justify a point, cite what the study did and found, not a theory linked to it.
Freud studied Little Hans, one boy's phobia, as a case study. Asked to justify with it, candidates used Freud's wider theory instead — the theory is not the study, so it misses the marks.
"Using the case study" means quote its own procedure and findings.
That candidates asked to justify using the case study wrote about Freud's theory rather than the Little Hans case study is recorded in the June 2022 Paper 2 Q32 examiner report.
Generalisability is not validity
Two AO3 terms students swap on a case study:
So it can have high validity but low generalisability at once.
Detailed does not mean objective
A case study's rich detail does not make it objective.
Because the researcher works closely with the case for a long time, they can become emotionally involved, so their interpretation may be subjective — shaped by personal opinion, not unbiased evidence. This researcher bias is a standard AO3 weakness, so do not treat depth as objectivity.
A case study can never be generalised
Students learn "a case study cannot be generalised" as an absolute. In fact findings from one case must be generalised with caution: what is true of one case may not hold for others, so alone it is weak evidence for a general claim. But its detail still matters — it can suggest hypotheses for larger studies, and a rare case can reveal what no large-sample study could.
A case study is always one person
Most textbook examples are individuals, so students think a case study is one person. The "case" is any single unit studied in depth:
What matters is that one case is studied in depth — so a group or event can be a case study too.
Explain: feature, why, consequence
For "explain a strength/weakness", build each point in three parts: the feature, why it follows, and its consequence. E.g. one case (feature) may be unique (why), so findings cannot be generalised (consequence). Describing the feature alone caps the mark.
The 12-mark methods essay
The 12-mark Evaluate essay can be set on the case study. AO1: an in-depth study of one case, several techniques, mostly qualitative. AO2: use the stimulus case. AO3: weigh depth and ecological validity against weak generalisability and objectivity, conclude.
Apply the case; AO3 needs AO2
On a scenario, application (AO2) means using the case's own detail — what was studied, the techniques used, what was found — not the researcher's name or a reworded stem. Tie every evaluation point to that case; losing AO2 also forfeits AO3, since AO3 needs AO2 present.
A case study is a research method that involves a detailed, in-depth investigation of a single case — one individual, small group, institution or event — usually studied over a long period. The defining feature is the single case studied in depth, not simply that it is "in-depth".
Case study — an in-depth, detailed investigation of a single case (one individual, group, institution or event), usually over time and combining several techniques.
Longitudinal — carried out over a long period of time, following the same case as it changes.
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