GCSE-ready- Home
- Lessons
- GCSE Psychology
- Experimental designs
Experimental designs
🎬 The doodle video for this lesson is coming soon. Subscribe on YouTube to see it first.
An experimental design is how participants are allocated to the conditions of an experiment. There are three designs.
Three designs
Repeated measures: the same participants take part in all conditions.
Matched pairs: participants are matched in pairs on important characteristics (such as age, IQ or gender). One of each pair goes into each condition.
Strengths and weaknesses
Choosing a design
Use independent measures when taking part in one condition would affect the other (for example, the same memory test twice).
Use matched pairs when participant variables are important but order effects would be a problem, as in Van Houtte and Jarvis (1995), where pet owners were matched with non-owners.
Bandura, Ross and Ross (1961) used groups matched on existing aggression levels.
A study compares memory in the morning and in the evening using the same 20 participants. Name the design and give one weakness.
- The same participants do both conditions: repeated measures.
- They may do better the second time because of practice: an order effect.
Answer: Repeated measures. Weakness: order effects such as practice or tiredness.
Independent measures uses different people in each condition (no order effects, but participant variables). Repeated measures uses the same people (no participant variables, but order effects). Matched pairs matches people on key characteristics (reduces both problems, but matching is hard).
The interactive lesson includes the diagrams for this topic.
Check you have got it
Answer 7 quick questions with instant marking. If you get one wrong, GCSE-ready shows you why and gives you another go. It is free, and you do not need an account.