Experimental design

Question 1

Repeated measures

Answer 1

All participants are used in both / all conditions.

Question 2

Repeated measures - advantages

Answer 2

Requires less participants.
Participants variables are controlled.

Question 3

Repeated measures - disadvantages

Answer 3

Order of tasks may cause boredom / fatigue.
Repeating tasks may mean unintended improvement of ability.
Order may act as a confounding variable.
Demand characteristics are more likely to occur.
Counterbalancing must take place.

Question 4

Independent groups design

Answer 4

Participants are assigned to either condition and only complete the experiment within that condition.
You need an equal number of participants in each group.

Question 5

Independent groups design - advantages

Answer 5

There is no issue with order effects.
Participants are less likely to guess the aim of the research.

Question 6

Independent groups design - disadvantages

Answer 6

The two groups are not the same therefore the results may be impacted by participant variables rather than the independent variable.
Requires double the number of participants - this costs more.

Question 7

Matched pairs design

Answer 7

Participants are paired together on a variable or variables relevant to the research.
One member of each pair is assigned to condition A and the other to condition B.

Question 8

Matched pairs design - advantages

Answer 8

Order effects and demand characteristics are less of problem.
Both groups are considered to be more evenly matched than in the independent groups design.

Question 9

Matched pairs design - disadvantages

Answer 9

No two people are identical so similarity may only be superficial and may still affect the dependent variable.
More time consuming and expensive.
Pre - testing may be required dependent upon the variables used to match the participants.

Question 10

Order effects

Answer 10

Issues that can arise due to the order in which participants may undertake the tasks set for them in a repeated measures design.
They may cause boredom or fatigue which may cause a deterioration of performance on the second task.
They may also use the first task has a practise - particularly for a skills based task.

Question 11

Counterbalancing

Answer 11

An attempt to control the order effects in a repeated measures design.
To counteract this one half of the group will experience the conditions in one order, the other half in the opposite order.

Question 12

Counterbalancing - AB or BA

Answer 12

Divide participants into two groups:
Group 1 - each participant does A then B.
Group 2 - each participant does B then A.
This is still a repeated measures design even though there are two groups of participants.
Comparison will be made for each participant on their performance on the two conditions.

Question 13

Counterbalancing - ABBA

Answer 13

All participants take part in each condition twice.
Trial 1 - condition A.
(Morning)
Trial 2 - condition B.
(Afternoon)
Trial 3 - condition B.
(Afternoon)
Trial 4 - condition A.
(Morning)
We then compare scores on trials 1 and 4 with trials 2 and 3.
This is still a repeated measures design.
We’re comparing the scores of the same person.

Question 14

Random allocation

Answer 14

An attempt to control participant variables in an independent groups design.
It ensures that the participants have the same chance of being in one condition as they do the other.

Question 15

Randomisation

Answer 15

Adopting a strategy for randomly determining the order of presentation of experimental conditions.
Can be used to decide the order of presentation of individual stimuli within a condition.
It’s also possible to combine an independent groups design with the matched pairs design.

Question 16

Standardisation

Answer 16

Using exactly the same formalised procedures and instructions for all the participants in the research study.