Experimental designs Flashcards
(15 cards)
What are the three types of experimental design in AQA Psychology?
Independent groups design
Repeated measures design
Matched pairs design
These are used to allocate participants to conditions in experiments.
What is an independent groups design?
Participants are split into separate groups, each doing one level of the IV.
No participant does more than one condition.
Strengths of independent groups design?
✔No order effects (fatigue/practice).
✔ Reduced demand characteristics as participants see only one condition.
Weaknesses of independent groups design?
✘ Participant variables may differ between groups.
✘ Requires more participants.
What is a repeated measures design?
Same participants take part in all conditions of the experiment.
Each participant is tested more than once.
Strengths of repeated measures design?
✔ Controls for participant variables.
✔ Fewer participants needed.
Weaknesses of repeated measures design?
✘ Order effects (practice, fatigue) may confound results.
✘ Increased chance of demand characteristics.
What is a matched pairs design?
Participants are paired based on relevant characteristics (e.g., age, IQ), then one from each pair is assigned to each condition.
Attempts to combine benefits of both independent and repeated designs.
Strengths of matched pairs design?
✔ Reduces participant variables.
✔ No order effects.
Weaknesses of matched pairs design?
✘ Matching can be difficult and time-consuming.
✘ Still possible to have some participant variables.
What are order effects and how are they controlled?
Order effects = changes in performance due to the order of conditions (e.g., fatigue or practice).
Controlled using counterbalancing: AB/BA method.
What is counterbalancing and when is it used?
Used in repeated measures designs to control for order effects.
Half participants do condition A then B, the other half do B then A.
Which design is most prone to demand characteristics?
Repeated measures, because participants take part in both/all conditions and may guess the aim of the study.
Which design is most efficient with small sample sizes?
Repeated measures, as fewer participants are needed for all conditions.
Which design is best for controlling participant variables?
Repeated measures fully controls them.
Matched pairs partially controls them.
