Repeated ANOVA

Question 1

What is sphericity?

Answer 1

 Variances across repeated measures conditions are likely to be similar, because they come from the same people!
 So, will have less random variance
 No individual differences between conditions
 Similar variance in the difference between conditions

Question 2

How does the G-G correction work?

Answer 2

 Calculation of variance and F ratio will remain the same
 Changes degrees of freedom: Reduced df means a bigger
effect needed to achieve a significant finding
 Correction is proportional to the magnitude of violation
 SPSS will automatically give you corrections.