ANOVA Extensions

Question 1

What is an ANCOVA?

Answer 1

ANOVA with the covariant partialled out

Question 2

What is a covariant?

Answer 2

Anything potentially correlated with the DV

Question 3

What is the basic ANCOVA procedure?

Answer 3

Semi-partial correlation between IV and DV with covariant partialled out of DV

Question 4

What are the assumptions for an ANCOVA?

Answer 4

Linear relationship between DV and covariant
Plot scatter plot to examine data distribution
Non-linear = violated
Homogeneity of regression slopes
Compare regression slopes for each level of IVs- should be similar otherwise assumption violated

Question 5

What is a MANOVA?

Answer 5

Examines if groups can be distinguished by a combination of DVs
(Multiple DVs)

Question 6

What are the tests the MANOVA F-test is based on?

Answer 6

Pillai-Bartlett Trace
Wilk’s Lambada
Roy’s Largest Root
Hotelling’s T-squared

Question 7

What are the assumptions of MANOVAs?

Answer 7

Homogeneity of the variance covariance matrices - analogous to homogeneity of variance
Test with Box’s test
Multivariate normality

Question 8

What are the follow ups for MANOVAs?

Answer 8

Separate ANOVAs for each DV
Significant MANOVA protect ANOVA against type 1 error
Can consider applying corrections
Linear discriminate analysis *