2.2.7 - counterbalancing, randomisation and order effects

Question 1

what is random allocation?

Answer 1

when pps are allocated to a condition of a study at random

Question 2

what is the purpose of random allocation?

Answer 2

in independent group experiment designs to control for the individual differences between pps in each condition - there is a greater chance of an even distribution of pp variation

Question 3

what effect can order effects have in a repeated measures experiment design?

Answer 3

they could improve performance in the second condition because pps have learnt the task and had practice at it in the first
they could worsen performance in the second condition because pps are tried or bored after the first

Question 4

how can order effects be controlled for?

Answer 4

using randomisation or counterbalancing, so pps experience the conditions in a different order

Question 5

what does randomisation involve?

Answer 5

selecting at random which condition of an experiment a pp does first

Question 6

what does counterbalancing involve?

Answer 6

randomly placing pps into two groups - one does condition A then condition B, and one does condition B then condition A

Question 7

what does counterbalancing do?

Answer 7

ensure the order effects of practice and fatigue are spread evenly between the conditions of an experiment so they don’t confound it

Question 8

when is the ABBA counterbalancing design used?

Answer 8

when there are unsymmetrical order effects - the order effect in the AB sequence orders isn’t equivalent to the order effect in another sequence order (BA)

Question 9

how does the ABBA counterbalancing design work?

Answer 9

pps complete the conditions twice - A,B,B,A, and then the mean score for each condition is taken

Question 10

what can a Latin square be used for?

Answer 10

to designate pps to one combination of ordering when there are more than two conditions in an experiment