Repeated Measures ANOVA

Question 1

What are the assumptions of the repeated measures ANOVA?

Answer 1

1. independence of errors and interaction effects.
2. normal population distribution within each treatment.
3. the error variance matrix must meet the sphericity assumption.

Question 2

How do you check the sphericity assumption in SPSS?

Answer 2

Test is not robust against this violation. SPSS shows four sphericity corrections.

1. sphericity assumed e=1
2. greenhouse-geller
3. huyn-feldt
4. lower-bound e = 1/(k-1)

Question 3

What is the syntax for a repeated measures ANOVA?

Answer 3

GLM Y1 Y2 Y3 
/WSFACTOR = time 3 Polynomial 
/METHOD = SSTYPE(3) 
/PLOT = PROFILE (time) 
/PRINT = DESCRIPTIVE ETASQ HOMOGENEITY 
/CRITERIA = ALPHA (0.05) 
/WSDESIGN = time

Question 4

Which contrasts can you use in a repeated measures ANOVA?

Answer 4

1. polynomial (time)
2. simple contrasts.
3. difference contrasts.
4. repeated contrasts.
5. Helmert contrasts.