Lesson 7 - Experimental Designs

Question 1

Experimental Designs

Answer 1

How the participants are assigned to different conditions

There are three main types including independent groups, repeated measures and matched pairs

Question 2

Independent Groups

Answer 2

Different participants are used in each of the conditions
Each group of participants is independent from one another
Participants are usually randomly allocated to each condition to balance out any participant variables

Question 3

Independent Groups Advantages

Answer 3

Order effect does not occur (when the sequence in which participants take part in conditions influences their performance or behaviour), participants may also get tired/bored/fatigued doing multiple conditions
Chance of demand characteristics decreases as participants only do one conditions so less chance to guess purpose of study
Saves time as both groups are tested at the same time

Question 4

Independent Groups Disadvantages

Answer 4

More participants needed

Always a chance that results are due to participant variables rather than manipulation of IV

Question 5

Repeated Measures

Answer 5

Each participant is tested in all conditions of the experiment

Question 6

Repeated Measures Advantages

Answer 6

As same people are measured, no participant variables between conditions
Half as many participants are needed compared to independent groups design

Question 7

Repeated Measures Disadvantages

Answer 7

Order effects may affect results, one way to avoid this is through counterbalancing
Demand characteristics more likely as participants in all conditions so high chance to guess purpose of study
Takes more time, especially if time gap between different conditions is required

Question 8

Counterbalancing

Answer 8

Half participants do one conditions while other half do other condition then switch
Does no eliminate order effects however controls impact of order effects and allows order effects to be distributed evenly across both conditions

Question 9

Matched Pairs

Answer 9

Different participants are used in all conditions (like independent groups design)
However, participants in two groups are matched on characteristics important for the study (age, gender, level of education)
Identical twins often used

Question 10

Matched Pairs Advantages

Answer 10

Less risk of order effects
Less risk of demand characteristics
Participant variables unlikely as groups are closely matched

Question 11

Matched Pairs Disadvantages

Answer 11

Twice as many participants required compared with a repeated measures design
Matching process is difficult
Matching process is time consuming