When are post-hoc tests used?
Only if an ANOVA was significant.
What are contrasts used for?
To evaluate specific predictions.
What are post-hoc tests used for?
To explore what is going on.
What does a Bonferroni correction take as C?
Number of corrections.
What does Scheffe’s correction take as C?
Number of possible linear combinations.
What does Sidak’s correction take as C?
Number of pairwise comparisons.
Using the studentised range distribution, what decreases the critical value?
Increasing sample size.
Using the studentised range distribution, what increases the critical value?
Increasing the number of levels/means you are comparing.
When should Tukey’s HSD be used?
When there are a large number of levels in a factor.
What are deviation contrasts?
Deviation of each level mean from the grand mean.
What are simple contrasts?
Deviation from a reference mean.
What are repeated contrasts?
Mean 1 vs. 2, 2 vs. 3, etc.
What are polynomial contrasts?
Linear, quadratic, etc.
What are difference contrasts?
Compares each level with the average of all previous levels.
What are Helmert contrasts?
Compared mean at each level with the average of all the subsequent (higher) levels.
Give 3 orthogonal contrasts.
Polynomial, difference, and Helmert.