Experimental design Flashcards
What is a repeated measures design?
1
- Each ppt takes part in every condition being tested, may be ctrl group
What are the pros of a repeated measures design?
2
- Control ppt variables, same person tested 2x
- Fewer ppt needed, ^data = conclusions^ dependable
What is an independent groups design?
1
- Diff ppt allocated to 2+ exprmtr groups, may be ctrl
What are the pros of an independent groups design?
2
- Avoid order effects (each ppt tested once)
- Avoids ppt guessing aim of exprmt
What are the cons of an independent groups design?
2
- No control of ppt variables (^IQ in groups)
- Needs more ppt
What is a matched pairs design?
2
- Ppt similar on key variables (memory) paired
- 1 member of pair placed in group A, other group B
What are the pros of a matched pairs design?
2
- Controls for ppt variables (matching)
- Avoids order effects
What are the types of order effects?
2
- Practice effect = ppt better on 2nd test (^better w exp)
- Fatigue effect = perform >well (bored/tired)
How can you deal with >control of ppt variables?
2
- Randomisation of ppt to conditions
- Ppt variables shouldn’t cluster in 1 particular group
How can you control order effects (repeated measures)?
3
- Counterbalancing, change order of conditions
- People doing con A = benefit from practice effect
- Condition B last = benefit from practice effect
What are the cons of a repeated measures design?
2
- Order effects
- Ppt may guess purpose of exp if doing both condition
What are the cons of a matched pairs design?
2
- Time consuming to match ppt
- May not control all ppt variables, match ones known to be relevant
How can you control extraneous variables (ppt/situational)?
2
- Variables held constant (similar age)
- Variables randomly allocated across conditions
