Experimental Design

Question 1

What are the strengths and weaknesses of independent design (different participants used in each condition of the independent variable and should be done by random allocation)

Answer 1

Strengths -
- avoids order effects (practice or fatigue) as people participate in one condition only

Weaknesses -

• more people are needed
• participant variables , eg age, gender, race etc

Question 2

Strengths -

• participant variables (individual differences) are reduced because the same p’s are used
• fewer people needed

Weaknesses -
- order effects . Order of conditions may have man effect on the p’s behaviour (controlled by counterbalancing)

What experimental design applies for these strengths and weaknesses?

Answer 2

Repeated measures

Question 3

What are the strengths and weaknesses for matched pairs? (each condition uses different participants but they are matched on important characteristics)

Answer 3

Strengths -

• reduces participant variables because the researcher has tried to pair up the p’s so each edition has people with similar characteristics and abilities
• avoids order effects and so counterbalancing is not necessary

Weaknesses -

• if a p drops out you lose 2 pp’s data
• time consuming to find closely matched pairs
• no one can be matched perfectly unless they are like identical twins