experimental designs

Question 1

independent group design?

Answer 1

• ppts are allocated to different groups and they experience different conditions.
• performance of groups is then compared.

Question 2

What are the strengths of an independent group design?

Answer 2

• order effects are not a problem
• ppts are less likely to guess the aim (demand characteristics)

Question 3

What are the weaknesses of an independent group design?

Answer 3

• Not the same in terms of participant variables which may reduce the validity. However, this can be reduced with random allocation.
  -more ppts are needed which means more time and money is spent

Question 4

What is a repeated measure design?

Answer 4

It is when all ppts take part in all conditions in which then the performance of both groups is compared.

Question 5

What are the strengths of a repeated measure design?

Answer 5

-Participant variables are controlled which increases the validity
- Less ppts are needed so less time is spent recruiting people

Question 6

What are the weaknesses of a repeated measure design?

Answer 6

• ppts have to do 2 tasks in which the order may be significant (order effects). This can be reduced using counterbalancing.
• order effects can be caused as ppts grow bored/fatigued which may cause a deterioration in performance
• on skill based tasks others may perform better
• ppts are more likely to guess the aims (demand characteristics?

Question 7

What is a matched pair design?

Answer 7

It is when pairs are first matched on variables which may affect the dependent variable. This is done by one pair being assigned to condition A and another pair being assigned to condition B.

Question 8

What are the strengths of a matched pair design?

Answer 8

• ppts only take part in 1 condition which means order effects and demand characteristics are less likely

Question 9

What are the weaknesses of a matched pair design?

Answer 9

• ppts can’t be matched exactly
• matching can be time-consuming and expensive which makes it less economical

Question 10

What is random allocation?

Answer 10

Ppts should be randomly allocated to different experimental conditions to reduce participant variables

Question 11

What is counterbalancing?

Answer 11

Half of the ppts take part in condition A and then condition B to reduce order effects

Question 12

What are extraneous variables (EV)?

Answer 12

Any variables other than the IV that may affect the DV if not controlled. These are essentially nuisance variables that don’t affect the DV much. these are easy to control (lighting, noise etc).

Question 13

What are confounding variables (CV)?

Answer 13

It is a kind of EV but it systematically varies with the IV which means you can’t tell if the change in the DV is due to the IV or CV

Question 14

What are demand characteristics?

Answer 14

Any cue from the researcher or the situation which may be interpreted by ppts as revealing the purpose of the investigation which may change the ppts behaviour.

Question 15

What are investigator effects?

Answer 15

Any effect of the investigator’s behaviour on the research outcomes which can include anything from the design to selection of ppts.

Question 16

What is standardisation?

Answer 16

Using exactly the same formalised procedures, instructions and environment for all ppts.