Eduqas A Level Psychology
Eduqas A Level Psychology Participants and Experimental Design Exam Questions
Free Eduqas A Level Psychology revision for Participants and Experimental Design: what you need to know, common mistakes and exam-style questions with answers. Covers target populations, sampling frames, nine sampling techniques including event and time sampling, and independent groups, repeated measures and matched pairs.
Practise Participants and Experimental Design with past papers
Once you have learnt this topic, find the Participants and Experimental Design questions in real Eduqas A Level Psychology past papers and mark them with the mark scheme. Doing lots of real questions is the quickest way to learn how examiners ask about each idea.
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About Eduqas A Level Psychology Participants and Experimental Design
This topic in Component 2 covers who takes part in research and how they are allocated to conditions. You need to define each sampling method, say how it would be carried out in practice, and judge how representative the resulting sample is. You also need the three experimental designs and ways of dealing with their problems, such as counterbalancing and random allocation. Examiners love to ask you to identify the sampling technique in a described study, to explain how you would obtain a stratified or random sample, or to choose an appropriate design for a novel scenario and justify your choice.
What you need to know
- Populations and sampling frames The target population is the group the researcher wants to generalise to. The sampling frame is the list of members of that population from which the sample is drawn, such as a school register.
- Random and systematic Random sampling gives every member of the sampling frame an equal chance, for example using a random number generator. Systematic sampling selects every nth person from the frame.
- Opportunity, self-selected and snowball Opportunity samples use whoever is available. Self-selected samples respond to an advert. Snowball sampling asks participants to recruit others, which is useful for hard-to-reach groups.
- Stratified and quota Both divide the population into subgroups in the right proportions. Stratified sampling then selects randomly within each subgroup; quota sampling uses opportunity sampling within each subgroup.
- Observational sampling Event sampling records every time a target behaviour occurs. Time sampling records behaviour at set intervals, for example every 30 seconds.
- Experimental designs Independent groups: different participants in each condition, so participant variables are a risk (use random allocation). Repeated measures: the same participants do all conditions, so order effects are a risk (use counterbalancing). Matched pairs: participants are matched on key variables, which is time-consuming.
Common mistakes in Participants and Experimental Design
- Calling any sample of students a random sample. Random sampling requires every member of the target population to have an equal chance of selection, usually from a full list.
- Mixing up stratified and quota sampling. Stratified selects randomly within each stratum; quota uses opportunity sampling within each.
- Saying counterbalancing removes order effects. It balances them across conditions so they do not systematically favour one condition.
- Confusing random sampling with random allocation. Sampling is how people are selected; allocation is how they are put into conditions.
- Writing 'the sample is biased' without explaining. State which group is over or under-represented and why that limits generalisation.
Try three Participants and Experimental Design exam-style questions
1. A school has 600 pupils: 360 girls and 240 boys. A researcher wants a stratified sample of 50. How many girls and boys should be selected? (2 marks)
Show the mark scheme answer
Girls: 360 / 600 x 50 = 30; boys: 240 / 600 x 50 = 20.
2. Explain how counterbalancing could be used in a repeated measures study on music and concentration. (3 marks)
Show the mark scheme answer
Divide participants into two groups; group A completes the task with music then without; group B completes it without music then with; so order effects such as practice or fatigue are balanced across conditions.
3. Explain one strength and one weakness of matched pairs design. (4 marks)
Show the mark scheme answer
Strength: participant variables are reduced because pairs are matched on relevant characteristics, and there are no order effects; weakness: matching is time-consuming and can never be perfect, so some participant variables remain.
Participants and Experimental Design FAQs
What does Eduqas A Level Psychology Participants and Experimental Design cover?
Target populations, sampling frames, all nine sampling methods including event and time sampling, and the three experimental designs with their controls.
Which paper is this examined in?
It is examined in Component 2, Psychology: Investigating Behaviour, a 2 hour 15 minute written paper worth one third of the A level.
Which sampling method should I recommend in a design question?
Choose one that fits the scenario and justify it: stratified for a representative sample with key subgroups, snowball for hard-to-reach groups, and opportunity when time and access are limited, noting the trade-off.
