Within-subjects ANVOA

Question 1

what is a within subjects ANOVA?

Answer 1

analysing the differences betweenthree or morelevels of an independent variable where all participants have taken part in all conditions.

Question 2

advantages of within-subjects ANOVA?

Answer 2

Controls for individual differencesbetween participants

Question 3

disadvantages of within-subjects ANOVA?

Answer 3

• Risk of carryover effects (can be mitigated through counterbalancing)
• Asymmetric carry-over effects
• Requires an assumption of sphericity.

Question 4

what is sphericity?

Answer 4

• assumption about variance
• The differences between each pair of’treatmentlevels’ should have equal variance.
• Only important if a variable has three or more levels

Question 5

what happens if sphericity os violated?

Answer 5

increased risk of Type 1 error

Question 6

what are the assumptions of within-subjects ANOVA?

Answer 6

1. data is ratio or interval (continuous)
2. Normal distributions
3. Independence of data
4. Sphericity

Question 7

steps to calculate a within-subjects ANOVA?

Answer 7

1. Partition the variability (I.e. calculate deviations)
2. Compute sums of squares
3. Compute mean squares
4. Calculate F-ratio

Question 8

what is SSt?

Answer 8

Total sum of squares

Question 9

what is SSa

Answer 9

between-condition sum of squares

Question 10

what is SSs?

Answer 10

within-subject sum of squares

Question 11

what is SSaxs

Answer 11

residual error term, how much variance is due to error

Question 12

what is an interaction?

Answer 12

when one level of your variable has a significant effect when combined with another