Case Study

Qualitative research

Definition

An in-depth investigation of a bounded system — an organisation, programme or event — using multiple evidence sources to answer how and why questions in real context.

A case study is an in-depth investigation of a bounded phenomenon in its real-world context — an organisation, a programme, an event or an individual. It is chosen when the boundary between the phenomenon and its context is unclear and when how or why questions are being asked.

Yin distinguishes single from multiple case designs and holistic from embedded units of analysis. A single case is justified when it is critical, unusual, revelatory or longitudinal; multiple cases allow replication logic, where cases are selected to predict either similar results or contrasting results for anticipated reasons.

Its hallmark is multiple sources of evidence — interviews, documents, archival records, observation and artefacts — converged through triangulation to strengthen construct validity. Define the case boundary explicitly, maintain a case study database as an audit trail, and remember that case studies generalise to theory rather than to populations.