Experimental Design

Question 1

Define ‘experimental design’

Answer 1

The organisation of participants across experimental conditions

Question 2

Name the 3 types of experimental design

Answer 2

1) Independent groups, 2) Repeated measures, 3) Matched pairs

Question 3

Define ‘independent groups’

Answer 3

Participants are allocated to just one experimental condition meaning different participants are used in each condition of the independent variable

Question 4

Define ‘repeated measures’

Answer 4

The same participants take part in each condition of the independent variable so all participants take part in all experimental conditions.

Question 5

Define ‘matched pairs’

Answer 5

Participants paired on a variable and then one of each pair allocated to each experimental condition. Identical twins best to use

Question 6

Give two advantages and disadvantages of independent groups design

Answer 6

• No order effects
• Less demand characteristics (less likely to guess aim)

-Participant variables have a bigger impact on results
- Need more participants (less economical)

Question 7

Give two advantages and disadvantages of repeated measures design

Answer 7

-Participant variables are controlled
-Less participants needed

-Demand characteristics, order effects

Question 8

What are order effects?

Answer 8

Occur in repeated measures design
Repeating 2 tasks could create boredom or fatigue leading to deterioration in performance on 2nd task. Or could lead to practice effects where participants’ performance improves.

Question 9

Give 3 advantages and 2 disadvantages of matched pairs design

Answer 9

-Reduce impact of participant variables
-Less demand characteristics
-No order effects

1. Time consuming
2. Not possible to control all participant variables as can only match on variables known to be relevant, but could be others are important.

Question 10

Outline one way to overcome order effects in a repeated measures design

Answer 10

Counterbalancing - Half the participants experience the conditions in one order, and the other half in the opposite order.

Question 11

Give one way to overcome the higher chance of participant variables in an independent groups design?

Answer 11

Random allocation→ Allocating participants to experimental groups or conditions using random techniques.