📊 Positivist methods give
Numbers, patterns and trends across many people. They show what is happening and how common it is.
Approaches to Research » Mixing Methods: Triangulation and Longitudinal Studies
What you'll learn this session
Study time: 30 minutes
Cambridge spec: 1.1.3
- What triangulation is and why sociologists use more than one method
- What a longitudinal study is, with the Up documentary series as an example
- Why researchers combine positivist and interpretivist methods
- The strengths and limitations of both approaches, such as attrition, cost and time
Why one method is not always enough
In 1964 a British television team filmed a group of seven-year-old children from very different backgrounds and asked them what they thought life would be like. Then they went back. Every seven years since, the same people have been filmed again, from teenagers to adults to grandparents. This is the Up series, and it began with Seven Up!
Few research projects last this long, but it shows a big idea. Sometimes a single snapshot is not enough. To understand society well, sociologists often combine different research methods and evidence. This lesson looks at two ways of doing that.
Key terms:
- Triangulation: using more than one method or source of evidence to study the same topic, so that the findings can be cross-checked.
- Methodological pluralism: the idea of using a mix of methods, rather than relying on only one.
- Longitudinal study: research that studies the same group of people over a long period of time.
- Sample attrition: when people drop out of a study over time, so the sample gets smaller.
Triangulation: cross-checking your findings
Like a detective checking several clues, triangulation cross-checks one topic with two or more methods
Think of a detective. One witness might be mistaken. But if a witness, a photograph and a fingerprint all point the same way, the detective can be much more confident. Triangulation works in the same way. A sociologist studies one topic using two or more methods or sources, then checks whether they agree.
Here is a made-up example. A researcher wants to know why some students leave school early. She might:
📝 Questionnaire
Send a questionnaire to 500 students. This gives numbers and patterns.
🗣️ Interviews
Interview 15 students in depth. This gives their own words and reasons.
📄 Records
Look at school attendance records. This is evidence that already exists.
If all three show that money worries are a main reason, she can trust the finding more. If they disagree, she knows she needs to look again. The idea of using a mixture of methods like this is called methodological pluralism.
Combining positivist and interpretivist methods
Remember, positivists prefer quantitative data and patterns, while interpretivists prefer qualitative data and meanings. Triangulation lets a researcher use both.
💬 Interpretivist methods give
Meanings, feelings and detail from a few people. They help explain why it is happening.
Each approach has gaps that the other can fill. Statistics can show that something is happening but not why. In-depth interviews can explain why but might only cover a few people. Used together, they give a fuller picture.
👍 Strengths of triangulation
- Findings can be cross-checked, so they are more trustworthy.
- Gives both patterns and meanings.
- Different methods cover each other's weaknesses.
👎 Limitations of triangulation
- Takes more time and costs more than one method.
- Needs a researcher skilled in several methods.
- Results from different methods may not agree, which can be hard to explain.
Longitudinal studies: following people over time
A longitudinal study is like a family photo album - it follows the same people again and again over many years
A longitudinal study studies the same group of people again and again over a long period, perhaps many years. Most research takes a snapshot of one moment. A longitudinal study is more like a film, because it shows how things change.
The Up series is a famous example. Because the same people were filmed every seven years from 1964, viewers can see how childhood, school, work, family and life choices shape a person over time. A researcher can use the same idea with questionnaires or interviews, going back to the same people every few years.
👍 Strengths of longitudinal studies
- Shows change over time, such as how a child's early life affects them as an adult.
- Helps to see which events come first, which helps to explain causes.
- Follows real people, so the information can be detailed and valid.
👎 Limitations of longitudinal studies
- Sample attrition: people move away, lose interest or die, so the group shrinks. Those who stay may not be typical.
- Time: it can take years or decades to get results.
- Cost: researchers must be paid and funded for a long time.
Longitudinal studies can also be triangulated. A researcher might survey the same people every few years and also interview some of them, mixing quantitative and qualitative data.
Common mistakes
Students often say triangulation just means "using lots of people". It does not. It means using different methods or sources on the same topic. Another mistake is thinking a longitudinal study asks lots of different people once. It follows the same people over time.
Exam-style question
Source A: A researcher wants to study how moving to a city affects young people. She sends a questionnaire to 300 young people who have just moved to a city, and she interviews 10 of them in depth. She then visits the same young people every two years for ten years.
(a) From Source A, identify two data collection methods the researcher used. [2 marks]
(b) Using information in Source A, explain two reasons why the researcher used more than one method. [4 marks]
(c) Explain one strength and one limitation of longitudinal studies. [4 marks]
Model answer
(a) Questionnaire (1). Interviews (1). (Revisiting the same people is the longitudinal design, not a method.)
(b) Reason 1: using both methods lets her cross-check her findings (1), so she can see whether the questionnaire results and the interview results agree (1). Reason 2: the questionnaire gives patterns across 300 young people (1), while the interviews explain why in the young people's own words (1).
(c) Strength: it shows how people change over time (1), so she can see how city life affects the same young people year by year (1). Limitation: sample attrition (1), because some of the young people may move away or drop out over ten years, so the sample shrinks and may no longer be typical (1).
Exam tip
In part (b), use the source. Give two separate reasons, say what each method gives (patterns, explanations) and link it to the researcher's study, rather than just writing "it is better".
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