Can you trust what researchers tell you?
Imagine two headlines. One says, "Most teenagers in the city love the new bus service." The other says, "Teenagers hate it." Both claim to be based on research. So who is right? A good sociologist does not just accept a result. They ask how the research was done, and whether anything might have pushed the results in the wrong direction.
This lesson gives you a toolkit for judging research. You will use it all through Paper 1, because you must be able to analyse and evaluate research choices, not just describe them.
Key terms:
- Bias: when research is unfairly pushed towards one result, so it does not give a true and balanced picture.
- Researcher bias: when the researcher's own opinions, hopes or background shape what they ask, see or write up.
- Respondent bias: when the people being studied give answers or behave in ways that are not truthful or natural.
- Interviewer effect: when the interviewer's age, gender, ethnicity, appearance or manner changes how the person answers.
- Hawthorne effect (observer effect): when people change their behaviour because they know they are being watched.
- Representativeness: how closely the sample matches the wider group being studied.
- Generalisability: how far the findings can be applied to people beyond the sample.
Bias: researcher and respondent
Bias can creep in from two sides. The researcher plans the study, and the respondents take part in it.
👩🏫 Researcher bias
The researcher may ask leading questions, choose a sample that suits their idea, notice only what supports their view, or leave out results they dislike. They may not do this on purpose. A researcher who loves a bus service might word every question so that it sounds good.
🙋 Respondent bias
People may not tell the truth. They might want to look good by giving the answer they think is "right", want to please the researcher, forget details, or exaggerate. A student asked how much homework they do may say more than they really do.
Bias lowers the quality of research. If the evidence is biased, the findings may not be true, and nobody should build a conclusion on them.
The interviewer effect
Who asks matters: the interviewer effect means age, clothes or reactions can change the answers people give
An interview is a conversation, and conversations are shaped by who is in the room. The interviewer effect happens when something about the interviewer changes the answers. This might be their age, gender, ethnicity, accent, clothes or the way they react.
For example, a young woman might feel less comfortable talking about family arguments with an older male interviewer than with someone her own age. She may hold back, or say what she thinks he wants to hear. The answers then show the effect of the interviewer, not just her real views.
The interviewer effect is a type of bias. It is mostly a problem for interviews, but a researcher who reads out a questionnaire face to face can cause it too.
The Hawthorne (observer) effect
Workers who know they're being watched may work harder - that's the Hawthorne (observer) effect
The Hawthorne effect is named after a series of studies in a factory in the USA, where workers changed how they behaved when they knew they were being studied. It is also called the observer effect.
Think about your own behaviour. Would you act exactly the same in class if a stranger sat at the back writing notes about you? Most people would not. They may work harder, behave better or act differently without even realising.
Why it matters
If people know they are being observed, what the researcher sees is not natural behaviour. This is a particular problem for observations, but it can happen in any method where people know they are being studied.
Using validity and reliability as evaluation tools
You already know what validity and reliability mean. Now you use them as tools to judge a study.
🎯 Validity
Ask: does this study give a true picture of what people really think or do? Bias, the interviewer effect and the Hawthorne effect all reduce validity, because the data is not a true picture.
🔁 Reliability
Ask: could another researcher repeat this study in the same way and get the same results? Standard questions and clear steps make a study easier to repeat. A very personal, unplanned approach is harder to repeat.
This gives you a simple way to write evaluation: name the problem, say which tool it affects, and explain why.
Representativeness and generalisability
Most researchers cannot study everyone, so they study a smaller group called a sample. The key question is: is the sample like the wider group?
A sample is representative if it has the same mix of people as the whole group, for example the same balance of ages, genders, ethnic groups and social classes. A study of "teenagers in the city" that only asks pupils from one private school is not representative.
If a sample is representative, the findings can be generalised, which means they can fairly be applied to the whole group. If it is not, the findings only tell us about the people in the sample. Large, well-chosen samples are usually more representative. Small, in-depth studies of a few people are usually less so.
📊 Often stronger
Large surveys with hundreds or thousands of respondents can show patterns across a whole population.
💬 Often weaker
Small interview or observation studies give deep, valid detail, but the findings may not apply to everyone.
How samples are chosen is covered in a later lesson, Sampling Frames and Sampling Techniques. For now, remember the link: representative sample, so generalisable findings.
How to evaluate a study in an exam
Use this simple chain whenever you are asked about a study:
- Spot the problem (for example, "people may not be truthful").
- Name the correct term (respondent bias).
- Explain the effect (the answers are not a true picture, so validity is lower).
- Link it to the study in the source, using the details you are given.
Worked example
A teacher researcher interviews 12 students at her own school about bullying. Because she is a teacher at the school, students may not be honest (interviewer effect and respondent bias), which lowers validity. Only 12 students from one school were chosen, so the sample is not representative and the findings cannot be generalised to all schools.
Common mistakes
Students often write "the sample was too small" without saying why that matters. Always add that it is not representative, so the results cannot be generalised. Another mistake is mixing up the Hawthorne effect (people know they are watched) with the interviewer effect (the interviewer influences the answers).
Exam-style question
Source A: A researcher wants to find out how teenagers feel about social media. She interviews 20 pupils from one school in her home town. The interviews take place in the head teacher's office. She is a former teacher at the school, and she later writes that most teenagers feel social media is good for them.
(a) From Source A, identify two problems with the way the research was carried out. [2 marks]
(b) Using information in Source A, explain two reasons why the findings may not be valid. [4 marks]
(c) Explain one strength and one limitation of using a sample of 20 pupils from one school, as in Source A. [4 marks]
Model answer
(a) Any two: only 20 pupils from one school were interviewed (1). The interviews were held in the head teacher's office (1). The researcher was a former teacher at the school (1).
(b) Reason 1: the interviews took place in the head teacher's office, so pupils may have felt nervous or afraid to criticise social media (1), which is respondent bias and lowers validity (1). Reason 2: the researcher is a former teacher, so there may be an interviewer effect, as pupils may say what a teacher wants to hear (1), meaning the answers are not a true picture (1).
(c) Strength: a small sample of 20 pupils is quick and cheap to interview (1), and each pupil can give detailed answers about their own feelings (1). Limitation: the sample is only 20 pupils from one school, so it is not representative of all teenagers (1), which means the findings cannot be generalised to other places or schools (1).
Exam tip
In part (b), do not just say "it is biased". Pick a specific point from Source A, name the effect, and say what it does to validity. That is how you reach all four marks.