ANOVA Flashcards
What is the Null Hypothesis in one-way ANOVA?
All means are equal?
What is the Alternative Hypothesis in one-way ANOVA?
The means are not equal.
What does a small F-statistic mean?
Smaller differences between means
What does a larger F-statistic mean?
Larger differences between means?
What does decreasing F do?
The within-group variances increases, so F is less likely to be significant.
How do you calculate the Grand Mean?
Take all means of Groups and Average
How do you calculate the Model Sum of Squares?
- Take the difference between each Group Mean and Grand Mean.
- Square these
- Multiply by no. in each group
- Sum.
How do you calculate the Residual Sum of Squares?
- Take difference between Group Means and Individual data points.
- Square each number
- Sum all the data points.
How do you calculate the F-statistic?
F= MSm/ MSr
What is an Omnibus Test?
Tests the overall significant of the model. A significant F states means all means differ from each other, or one does.
What sort of distribution is an F?
One-tailed, because all differences are squared and positive.
What does the F statistic tell you?
About the effects in both directions, so cannot halve the p value for one tailed test if directional prediction, because the test is already one-tailed.
What are the three ANOVA assumptions in between-subjects?
- Observations should be independent
- Variances in each condition should be similar (homogeneity of variances)
- Distributions within groups should normally distributed
How do you test the Homogeneity of Variance between conditions?
The Levene Test
How does one run the Levene Test? And why do we want it to be non-significant?
If the variances in the population are equal, differences will be equal.
If it is significant we have violated our assumption of homogeneity of variance.
We want this test to be non-significant