Experimental design

Question 1

Independent groups design

Answer 1

If 2 groups in an experiment consist of different individuals then this is an independent groups design.

e.g. if we are trying to discover if girls are less aggressive than boys, then we obviously need 2 separate groups, namely boys and girls.

Question 2

Repeated measures

Answer 2

Use the same individuals and test them on 2 or more separate occasions.

E.g. find out if people remember information better in a silent condition or a noisy condition

Question 3

Matched pairs

Answer 3

Participants can be matched on variables which are considered to be relevant to the experiment in question.

For example, pairs of participants might be matched for age, gender and their scores from intelligence or personality tests.

Question 4

Independent groups design pros/cons

Answer 4

No control of participant variables e.g. natural intelligence, height

Need twice as many participants

No order effects

Question 5

Repeated measures pros/cons

Answer 5

Order effects e.g. boredom, fatigue

One condition harder than the other

May guess aim of experiment (lowers internal validity)

Less expensive

Question 6

Matched pairs pros/cons

Answer 6

Very time consuming

Can only match on variables known to be relevant may not match on things not known to be important