Repeated Measures Design
- One condition - may be more difficult than another.
- For Example: whether people remembered more in the morning than in the afternoon, give p's memory test and a diff one in afternoon.
- However, one test may be easier than the other.
- DV - due to extranous variables (easier test) rather than IV.
- May guess purpose of experiment in 2nd test - effect behaviour.
- For example: purposley doing worse in the 2nd so it appears they dont work aswell in the afternoon.
- Conditions may affect performance (order effect)
- May do better bc - less anxious
- OR worse because of boredom of same test.
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dealing with limitations - Repeated Measures Desig
- Make test equivalent - create 40 words and randomly allocate to 2 lists.
- Use a cover story about purpose - prevent them guessing what its about.
- Counterbalancing - tested first or second in equal amounts.
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Independent Groups Desgin
- No control over participant variables
- For example : p's in group 1 may happen to have better memories than group 2.
- 2X as many participants
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Dealing with imitations - Independent Groups Desig
- Randomly allocate p's to conditions - theoretically distrubutes participant variables evenly.
- MORE money and MORE time.
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Matched Pairs Desgin
- Match p's on key variables - start with a large group of p's to ensure you obtain matched pairs on key variables.
- May not control all p's variables - only match on relevant variables - others may be important.
- For Example: memory experiment - might match on memory ability but may find out p's have had a programme to boost memory skills - should of matched on this.
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dealing with limitations - matched pairs
- Restrict matching variables - make it easire.
- Conduct a pilot study - consider key variables.
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