4. Repeated measures ANOVA Flashcards
What are two advantages of a repeated measures design?
- It’s more economical with respect to sample size
2. Reduces error variability as between-subjects error is ignored.
What are levels called in repeated measures design?
Repeats
What are the two points of difference of repeated measures compared to between-subjects ANOVA?
- Contrast coefficients must be normalised
2. Separate error terms
What is error in repeated measures
Subject-treatment interaction. Why Pp1 scores +5 in a condition and Pp2 scores +3.
What is the formula for normalising contrast coefficients?
Divide each one by the square root of the sum of the squared contrast coefficients.
Do F and p change when coefficients are normalised in repeated measures?
No, just the SS changes.
What is error variability for contrasts in repeated measures?
The differences in contrast scores across participants.
What is sphericity?
The equality of variances of differences between treatment levels. Is the variance the same across all the repeats. Basically same as homogeneity of variance.
How do you check if sphericity is violated?
Check p in Mauchly’s test of sphericity. If p<.05 conclude that sphericity is violated and use adjustment method - Greenhouse-Geisser etc.
What’s the difference between a 2x3 design and a (2x3) design?
2x3 is between-subjects
(2x3) is within-subjects
How many groups are there in a repeated measures design?
One. With J repeats.
How many conditions/repeats in a 3 x (3) design?
9 conditions, 3 repeats
