W6 - 1-Way Repeated Measures ANOVA Flashcards
Define Effect size
Standardised way of telling how large the effect of our experimental manipulation was.
% of variability in the DV explained by the IV
What is effect size critical for?
Power calculations when planning a new study.
Partial eta squared
Effect size of 0.01
Small effect
Partial eta squared
Effect size of 0.06
Medium
Partial eta squared
Effect size of 0.14
Large effect
Why might the partial eta squared be seen as a biased estimate?
Due to only using the sums of squares
Why should a repeated measures ANOVA be used whenever possible?
Allows recruitment of fewer subjects for the same experimental power
Accounts for ind differences
When should you not use a repeated measures ANOVA
When examining differences across groups of ind (i.e special pop)
When order effects are too problematic
If experiment is too long or boring as drop out rate might incr
What is the F ratio examining in the repeated measures ANOVA
The wanted (effect) and unwanted (error) variance WITHIN your group of participants.
Allows us to ignore the between subject variance
Assumptions of the repeated measures ANOVA
Interval ratio scale data
Data normally distributed
Sphericity
What does sphericity test
Variances of the differences between each condition
When is the assumption of sphericity met?
When the relationships between experimental conditions is roughly equal.
What does Mauchlys test of sphericity test?
Whether the variances of the differences between conditions are equal.
Mauchlys test of sphericity
> 0.05
Variances of the differences are roughly equal = assume sphericity
Mauchlys test of sphericity
<0.05
Variances of the conditions differences scores are NOT equal = NO sphericity
