Experimental design

Question 1

What is a repeated measures design?

1

Answer 1

• Each ppt takes part in every condition being tested, may be ctrl group

Question 2

What are the pros of a repeated measures design?

2

Answer 2

• Control ppt variables, same person tested 2x

- Fewer ppt needed, ^data = conclusions^ dependable

Question 3

What is an independent groups design?

1

Answer 3

• Diff ppt allocated to 2+ exprmtr groups, may be ctrl

Question 4

What are the pros of an independent groups design?

2

Answer 4

• Avoid order effects (each ppt tested once)

- Avoids ppt guessing aim of exprmt

Question 5

What are the cons of an independent groups design?

2

Answer 5

• No control of ppt variables (^IQ in groups)

- Needs more ppt

Question 6

What is a matched pairs design?

2

Answer 6

• Ppt similar on key variables (memory) paired

- 1 member of pair placed in group A, other group B

Question 7

What are the pros of a matched pairs design?

2

Answer 7

• Controls for ppt variables (matching)

- Avoids order effects

Question 8

What are the types of order effects?

2

Answer 8

• Practice effect = ppt better on 2nd test (^better w exp)

- Fatigue effect = perform >well (bored/tired)

Question 9

How can you deal with >control of ppt variables?

2

Answer 9

• Randomisation of ppt to conditions

- Ppt variables shouldn’t cluster in 1 particular group

Question 10

How can you control order effects (repeated measures)?

3

Answer 10

• Counterbalancing, change order of conditions
• People doing con A = benefit from practice effect
• Condition B last = benefit from practice effect

Question 11

What are the cons of a repeated measures design?

2

Answer 11

• Order effects

- Ppt may guess purpose of exp if doing both condition

Question 12

What are the cons of a matched pairs design?

2

Answer 12

• Time consuming to match ppt

- May not control all ppt variables, match ones known to be relevant

Question 13

How can you control extraneous variables (ppt/situational)?

2

Answer 13

• Variables held constant (similar age)

- Variables randomly allocated across conditions