Can a thesis about one school, one company or one policy produce knowledge that examiners take seriously? Yes, if it follows a recognized case study methodology rather than a narrative of what happened. Committees regularly return case study theses because the case was never defined, the evidence came from one source only, or the analysis simply repeated interview quotes.
This article is part of our guide How to Write a Master’s Thesis by the Mastermind PhD team and relates to our Research Proposal support service. Sources last checked: November 2026.
This guide explains what a case study is, the main designs, how to choose and bound the case, the sources of evidence, the analysis strategies, and the quality checks that make the design defensible in a master’s thesis.
What is case study methodology? It is a research approach that investigates a contemporary phenomenon in depth and within its real-life context, especially when the boundary between phenomenon and context is not clear (Yin, 2018). It relies on several sources of evidence that converge on the same questions, and it can be qualitative, quantitative or mixed. The “case” is a bounded unit: an individual, an organization, a program, an event or a process.
When is case study methodology the right choice?
Yin (2018) links the choice to three conditions:
- The research question asks “how” or “why”, for example “How did the university implement blended learning?” rather than “How many students use it?”.
- The researcher has little control over events. If you can assign participants to conditions, an experiment is more suitable.
- The focus is contemporary, so that people can be interviewed and events observed. Purely past events are usually the territory of historical research.
Case study methodology is also appropriate when the context is part of the explanation, so that separating the phenomenon from its setting would remove what you want to understand.
What are the main case study designs?
| Classification | Types | Use in a thesis |
|---|---|---|
| Number of cases (Yin) | Single case, multiple cases | Single for a critical, unusual or revelatory case; multiple for comparison and replication |
| Units of analysis (Yin) | Holistic, embedded | Embedded when the case contains subunits, such as departments within one company |
| Purpose | Exploratory, descriptive, explanatory | Matches the research question |
| Interest (Stake, 1995) | Intrinsic, instrumental, collective | Intrinsic when the case itself matters; instrumental when it illustrates a broader issue |
A master’s thesis often uses a single case or two to four cases, because each case requires substantial fieldwork. Name the design explicitly in the methodology chapter with its source.
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How do you select and bound the case?
Selection must be purposeful and justified, not based only on convenience. Flyvbjerg (2006) describes information-oriented selection strategies:
- Extreme or deviant cases, unusually successful or unsuccessful, which reveal mechanisms.
- Maximum variation cases, different on one dimension, to see how context changes the process.
- Critical cases, where “if it holds here, it will hold anywhere”.
- Paradigmatic cases, which highlight general features of a phenomenon.
Then bound the case: state the time period, the place, the people and the activities included and excluded. Baxter and Jack (2008) stress that clear boundaries keep the study from trying to answer everything. Access matters too; confirm in writing that the organization will provide interviews and documents before you commit.
Which sources of evidence should you use?
Yin (2018) lists six sources. Sound case study methodology combines at least three.
- Documentation: reports, minutes, policies, emails, websites.
- Archival records: databases, budgets, enrollment figures, service records.
- Interviews: usually semi-structured, with participants in different roles.
- Direct observation of meetings, classrooms or workplaces.
- Participant observation, when the researcher takes part in the setting.
- Physical artifacts: tools, products, learning materials.
The value lies in triangulation: when interviews, documents and observation point to the same conclusion, the finding is stronger than any single source can make it.
How do you analyze case study data?
Collecting rich data is the easy part of case study methodology. For analysis, Yin (2018) describes five techniques:
- Pattern matching: comparing an empirically observed pattern with a predicted one from theory.
- Explanation building: developing a causal explanation step by step and testing it against the evidence.
- Time-series analysis: tracing changes over time against expected trends.
- Logic models: matching an expected chain of events (inputs, activities, outcomes) with what actually happened.
- Cross-case synthesis: in multiple-case designs, building a table across cases to identify similarities and differences.
Many master’s theses combine one of these strategies with thematic coding of interviews and documents. The coding is a tool; the strategy is what turns codes into an answer to the research question.
How do you demonstrate quality in a case study?
| Quality test (Yin, 2018) | Tactic | Phase |
|---|---|---|
| Construct validity | Multiple sources of evidence; chain of evidence; participants review the draft | Data collection and writing |
| Internal validity (explanatory studies) | Pattern matching, explanation building, addressing rival explanations | Analysis |
| External validity | Theory in single cases; replication logic in multiple cases | Design |
| Reliability | Case study protocol; case study database | Data collection |
A case study protocol (questions, sources, procedures) and a case study database (organized notes, transcripts and documents) are inexpensive and very persuasive in a thesis appendix. They show that another researcher could follow your steps, which is the core promise of a transparent case study methodology.
How do you write the case study methodology chapter?
A clear structure helps examiners follow your reasoning:
- Research approach and justification for a case study design.
- Design type (single or multiple, holistic or embedded) with references.
- Case selection criteria and case boundaries.
- Participants and sampling within the case.
- Data sources, instruments and fieldwork timeline.
- Analysis strategy and coding procedure.
- Quality measures, ethics approval and consent.
- Limitations, including the scope of generalization.
On generalization, be precise. A case study does not generalize statistically to a population; it generalizes analytically to theory (Yin, 2018). Flyvbjerg (2006) argues that the view that one cannot generalize from a single case is a misunderstanding, provided the case is chosen strategically.
Which mistakes weaken a case study thesis?
- Calling a survey of one organization a case study without multiple sources of evidence.
- No clear boundaries, so the study drifts across topics.
- Selecting the case only because it was accessible and saying nothing more.
- Reporting long quotations without analysis or connection to theory.
- Claiming that findings apply to all organizations of the same type.
- Ignoring rival explanations for what happened.
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Frequently asked questions
Is a case study qualitative or quantitative?
Case study methodology can be either, or mixed. Most master’s case studies are mainly qualitative, combining interviews and documents, but a case study can include survey data or performance records from the same case.
How many cases should a master’s thesis include?
There is no fixed number. One well-justified case is acceptable, and two to four cases allow comparison within a master’s timeline. Eisenhardt (1989) suggested four to ten cases for building theory, which is usually more than a master’s project can handle.
How many interviews do I need within a case?
Enough to cover the main roles and perspectives in the case and to reach the point where new interviews add little. Report the number, the roles and how you decided to stop, rather than citing a single fixed figure.
What is the difference between a case study and ethnography?
Ethnography focuses on culture and usually requires long immersion in a setting. A case study focuses on a bounded unit and a specific question, and can be completed with shorter fieldwork using several sources.
Do I need ethics approval for a case study?
Usually yes, because a case study involves people and often organizational documents. Check your university’s ethics procedure, obtain the organization’s permission, and protect the identity of the case and participants where needed.
Sources
- Yin, R. K. (2018). Case Study Research and Applications: Design and Methods (6th ed.). SAGE.
- Stake, R. E. (1995). The Art of Case Study Research. SAGE.
- Flyvbjerg, B. (2006). Five misunderstandings about case-study research. Qualitative Inquiry, 12(2), 219–245. https://doi.org/10.1177/1077800405284363
- Eisenhardt, K. M. (1989). Building theories from case study research. Academy of Management Review, 14(4), 532–550. https://doi.org/10.5465/amr.1989.4308385
- Baxter, P., & Jack, S. (2008). Qualitative case study methodology: Study design and implementation for novice researchers. The Qualitative Report, 13(4), 544–559. https://doi.org/10.46743/2160-3715/2008.1573
Sources last checked: November 2026. This article is general educational guidance and does not replace your university regulations or your supervisor’s instructions. How we prepare our content.