Experimental Designs

Question 1

What is the structure of repeated measures?

Answer 1

• All pps take part in all conditions of the experiment

Question 2

What are the evaluation points relating to Repeated measures?

Answer 2

• Limitation of order effects (solved by counterbalancing)
• Boredom or fatigue affects performance. Or pps performance improves due to practice, order is a confounding variable.
• Likely pps will work out study aim, demand charecteristics more prevalent than in IG.
• Strength, pps variables controlled (higher validity), fewer pps needed (cheaper and quicker)

Question 3

What is the idea behind Random Allocation?

Answer 3

• An attempt to evenly distribute pps differences across experimental conditions in an independent group design

Question 4

What are the evaluation points of the matched pairs model?

Answer 4

• Pps only take part in a single condition so order affects and demand characteristics are not an issue
• Doesn’t fully erase pps variables
• Matching pps may be time-consuming and expensive (particularly if pre-test is necessary), less economical

Question 5

What is the structure of a Matched Pairs design?

Answer 5

• Pps are matched on a variable important to the experiment and then one of each pair is allocated to a different condition

Question 6

What are the evaluation points relating to the independent groups design?

Answer 6

• Biggest issue if pps are not the same in terms of pps variables. So, change in DV may be to do with variables rather than IV, differences = confounding variable and reduce validity (solved by random allocation)
• Less economical that RM as each pps contributes only 1 result. Increases time + money recruiting pps.
• Strength is order effect are not an issue and pps are less likely to guess the aim

Question 7

What is the structure of the Independent groups design?

Answer 7

• Two separate groups are involved, each group does one of the conditions of the experiment

Question 8

What is the concept of counterbalancing?

Answer 8

• An attempt to control for order effects in a repeated measures design: half the pps do the conditions in one order and the other half in the opposite order