Experimental designs
Cards (9)
- Repeated measures design:
- Each participant takes part in every condition under test.
- Each condition represents one level of the Independent variable
- there may also be a control condition
- independent measures design:
- Participants are allocated to two (or more) experimental groups representing different levels of the IV.
- There may also be a control group
- Matched participants design:
- Participants who are similar on key variables (eg memory ability, age) are paired. One member of the pair is placed in group A and the others in group B.
- This means there are two groups of participants. Each group is given one level of the IV.
- Positive of Repeated measures:+ Good control of participant variables , since same person is tested twice.+ Fewer participants needed than in the independent measures design.
- Negative of repeated measures:- Practice effect. Student may be better and had adapted from the first condition.- Participants may guess the purpose of the experiment.- condition A may be easier than condition B
- Independent measure positives:
- Avoids order effects because each participant is only tested once.
- Avoids participants guessing the aims of the experiment
- Negatives of Independent measures design:- No control of participant variables. Participants in group A may be more intelligent that is why group A had higher on the test than group B.- Needs more participants than repeated measures design. If there is 20, they will be split between the two groups. And collect data only for 10 people.
- matched participants positive:+ Acts as a control for participant variables because of the matching (like repeated measures)+ Avoids order effects because it is like an independent measures design.
- Matched participants negative:- Very time consuming to match participants on key variables- May not control all participant variables because you can only match on variables known to be relevant, but it could be that other variables are important.