10. Experimental Design

Question 1

see pg98 for research example (read on throughout page for eg for each design)

Question 2

3 Experimental designs

Answer 2

1. Independent groups design
2. Repeated measures design
3. Matched pairs design

Question 3

What is an Independent groups design

Answer 3

• Means there are different participants in each group.
• There are 2 separate groups of P’s. One group takes part in condition A, the other takes part in condition B
• This avoids the problem that if all the P’s did the test in both conditions, any improvement in performance might be due to them having 2 goes at the task (which would be a confounding variable).

Question 4

ADVANTAGES of Independent groups design

Answer 4

1. No order effects - no one gets better through practice (learning effort) or gets worse through being bored or tired (fatigue effect).

Question 5

DISADVANTAGES of Independent groups design

Answer 5

1. Participant variables - differences between the ppl in each group might affect the results.
   (eg. One group may just coincidentally have ppl who are better at the research task than the other group - so we cant safely compare groups).
2. No. of participants - twice as many P’s are needed to get the same amount of data, compared to having everyone do both conditions.

Question 6

What is a Repeated measures design

Answer 6

• There is only 1 group of participants. This group takes part in both conditions.
• You are able to compare the performances in each condition (A & B) knowing the differences weren’t due to participant variables.

Question 7

ADVANTAGES of Repeated measures design

Answer 7

1. Participant variables - now the same ppl do the test in both condition, so any differences between individuals shouldn’t affect the results.
2. No. of participants - FEWER P’s are needed to get the same amount of data.

Question 8

DISADVANTAGES of Repeated measures design

Answer 8

1. Order effects - if all P’s did condition A first, any improvement in condition B could be due to practice, not the specific condition of condition B.

Question 9

What is a Matched pairs design

Answer 9

• There are 2 separate groups, but this time they are matched into pairs for certain qualities (age, sex, personality, etc.). One of each pair is randomly assigned to take part in condition A, the other takes part in condition B.

Question 10

ADVANTAGES of Matched pairs design

Answer 10

1. No order effects - there are different ppl in each condition.
2. Participant variables - important differences are minimised through matching. Can be more sure the IV caused differences in DV rather than big differences between the 2 groups.

Question 11

DISADVANTAGES of Matched pairs design

Answer 11

1. No. of participants - need twice as many ppl compared to repeated measured.
2. Practicalities - time-consuming & difficult to find P’s who match.