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Case Studies » Case Studies and Triangulation

What you'll learn this session

Study time: 30 minutes

Cambridge spec: 7.4.1, 7.4.2

What a case study is and what it looks at
The five ways a case study can collect data
What triangulation means and why researchers use it
The strengths and weaknesses of case studies, and how to apply them to a new scenario

So far you have looked at observations, questionnaires and interviews, one at a time. A case study is different. It can use several of these methods together to build a full picture of one person, one group or one event. This is part of Paper 2 Section D, the non-experimental methods questions.

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What is a case study?

Most research studies lots of people and looks for patterns. A case study goes the other way. It takes one individual, group or event and looks at it in great depth, often over a long time.

Key terms:

Case study: an in-depth investigation of a single individual, group or event.
Triangulation: comparing data collected using different methods to see if they agree.

You have already met two examples in this course: the study of the amnesia patient HM, and Hewitt's study of schemas and language. Each one focused on a very small number of people. You do not need to re-learn those studies here. Just remember that they are case studies.

How a case study collects data

A case study does not rely on one method. Researchers can use any of these five ways of collecting data:

🧠 Tests

Standard tests that give a score, such as a memory test or a reading test.

🧩 Tasks

Things the person is asked to do, such as copying a drawing or sorting objects.

👁 Observations

Watching and recording what the person or group does in everyday life.

📝 Questionnaires

Written questions, perhaps for the person, their family or their teachers.

🎤 Interviews

Spoken questions to the person or to people who know them well.

Because the researcher uses several methods, the case study produces a lot of rich detail about the one case.

Triangulation

Imagine a researcher studies a girl called Mina who has stopped speaking at school. The researcher gathers data in three ways:

An observation of Mina in the playground shows she avoids other children.
An interview with her teacher says she seems very anxious in groups.
A questionnaire completed by Mina herself shows she feels nervous when others look at her.

All three sources point the same way. This is triangulation: comparing the data from different methods to see if they agree.

Learn this

Triangulation = comparing data from different methods to see if they agree. If they do, the researcher can be more confident the findings are correct. If they do not, the researcher knows something needs a closer look.

Using one method alone could be misleading. Mina might hide her feelings in an interview but show them in her behaviour. Checking each method against the others helps the researcher spot this.

Strengths and weaknesses

✅ Strength: rich detail

The researcher collects a great deal of detailed information about the case. This gives a deep understanding that a short questionnaire to hundreds of people could not give. It can also study unusual cases that cannot be set up in an experiment.

❌ Weakness: hard to generalise

The study is of only one case, so the findings may not be true for other people. Mina's story may be very different from another child's. The researcher cannot be sure the results apply to everyone.

Applying it to a new scenario

Worked example

A researcher wants to understand how one teenage footballer, Dev, recovers from a serious leg injury over six months.

Is this a case study? Yes. It is an in-depth investigation of a single individual.

Methods the researcher could use: a fitness test each month (test), asking Dev to complete a balancing exercise (task), watching him at training (observation), a written mood diary (questionnaire) and talking to him and his coach (interviews).

Triangulation: if the fitness test, the training observation and the coach's interview all show steady improvement, the researcher can be more confident Dev is really recovering.

Strength: very detailed information about how recovery happens. Weakness: other injured players may recover differently, so the findings are hard to generalise.

Common mistakes

Saying a case study only uses interviews. It can use tests, tasks, observations, questionnaires and interviews.
Describing triangulation as "using lots of participants". It is about comparing different methods, not different people.
Saying the weakness is that case studies are "small". Say the findings are hard to generalise because only one case was studied.
Writing "rich detail" without explaining it. Say what the researcher learns that they could not learn from a quick method.

Exam-style question

A researcher carries out a case study of a group of six pupils who have just moved from a small village school to a large secondary school.

(a) Identify two methods the researcher could use to collect data in this case study. [2 marks]

(b) Explain what is meant by triangulation. [2 marks]

Model answer

(a) Observations of the pupils in the playground (1) and interviews with the pupils about how they feel (1).

(b) Triangulation is comparing data collected using different methods (1) to see whether they agree, for example whether the observations match what pupils say in interviews (1).

(c) The findings are hard to generalise (1) because only six pupils were studied, so other pupils moving to a large school might have very different experiences (1).

Exam tip

When a question asks about a weakness of a case study, link it to the scenario. Name the case in the question and say why its results might not apply to others.

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