Types of experimental design

Question 1

repeated measures?

Answer 1

Each participant takes part in every condition

Question 2

independent groups?

Answer 2

The participants are allocated to two groups where they take part in two different conditions

Question 3

Matched pairs?

Answer 3

this is where pairs of participants are matched in terms of a key variable for example: age

Question 4

what are further disadvantages of repeated measures?

Answer 4

1) order of the condition (order effects) might have an effect on performance. Participants may do better on second test due to the practice effect or being less anxious. Some participants may do worse on the second test due to being bored of completing the test

2) When they do the second test they may guess the purpose of the experiment which may affect there behaviour. for example: they may do worse in the tests due to demand characteristics(may have tried to work out what they are testing)

Question 5

What are further disadvantages of independent groups?

Answer 5

1) cannot control affect of participant variables. participants in group a might have a better memory than the participants that are in group B. This would further act as a confounding variable

2) independent groups design needs more participants than repeated measures design in order to be able to collect the same amount of data

Question 6

What are the further disadvantages of matched pairs?

Answer 6

1) very time consuming difficult too match participants on key variables. researcher has to make a start with a large sample to ensure they can obtain matched pairs on key variables

2) impossible to be able too be able to control all participant variables ,only match on variables that are known to be relevant, could be that others may be important. for example: within a memory experiment you might have matched on memory abilities and later you find that some of the participants have been involved within a teaching programme to boost memory skills but you should have matched on this.

Question 7

ways we could deal with the disadvantages repeated measures?

Answer 7

1) use different tests too reduce practice effect - must be equivalent - constructing a test on 40 items and randomly allocating items to test A and B

2) order effects can be dealt with counterbalancing (allows that each condition tested first or second in equal amounts)

in order to stop the participants from guessing the aims of the study, a cover story can be presented about the purpose of the test

Question 8

ways we could deal with the disadvantages of independent groups design?

Answer 8

1) randomly allocate participants too conditions which distribute participant variables equally.
can be done by using things like putting names in a hat and drawing one

Question 9

Ways we could deal with the disadvantages of matched pairs?

Answer 9

1) restrict the number of variables to match on to be able to make it easier
2) conduct a pilot study (small scale trial run of the study to test any aspects of the design, with a view for making improvement’s) to consider key variables that might be important when matching

Question 10

what are the strengths of the independent groups design?

Answer 10

• participants are less likely too work out the aims than repeated measure design they only take part in one condition this then further reduces demand characteristics
• reduces order effects as the participants only take part within one condition

Question 11

What are the strengths of the repeated measures design?

Answer 11

• repeated measures design needs half the participants compared too independent groups design for the same amount of data
• participant variables between the conditions is not a problem as the participants take part in both conditions

Question 12

What are the strengths of matched pairs?

Answer 12

• reduces participant variables as the participants are matched based on certain characteristics
• it has no order effects as the participants only take part within one condition