Week 6 - Lecture 6 Flashcards
What does ANOVA tell you?
ANOVA tells you if there’s a difference somewhere between 3+ group means
What do follow-up tests help you determine after ANOVA?
Follow-up tests help you find out which groups are different
What are the two main types of follow-up tests?
- Planned Comparisons (A Priori)
- Unplanned Comparisons (Post Hoc)
What are Planned Comparisons?
You decide before collecting data what comparisons to make
Why are Planned Comparisons considered more powerful?
They have less error risk
What statistical method do Planned Comparisons use to control Type I error?
Uses Bonferroni t test
What are Unplanned Comparisons?
You decide after seeing the results
What is a characteristic of Unplanned Comparisons?
More exploratory
What test is used for pairwise comparisons in Unplanned Comparisons?
Tukey
What test is used for all comparisons in Unplanned Comparisons?
Scheffé
What are Linear Contrasts?
A fancy way of doing multiple t-tests without inflating error
What do Linear Contrasts compare?
- One mean vs another mean
- An average of group means vs another group
How do you set up Linear Contrasts?
Each group gets a weight (called A)
What are the rules for setting up Linear Contrasts?
- Groups not involved = weight of 0
- Positive weights vs negative weights
- Weights must add up to zero
- Use whole numbers
What is the formula for Linear Contrast (L)?
L = ∑(A_j × group mean)
What is the formula for Bonferroni t?
t = L / (MS_error × ∑A_j²)
What does MS_error represent in the Bonferroni t formula?
MS_error is from the ANOVA table
What are Orthogonal Contrasts?
Each comparison asks a different question
What conditions must Orthogonal Contrasts satisfy?
- Be valid linear contrasts
- Have sum of products of weights = 0
- Be no more than (k−1) comparisons
How many orthogonal contrasts can you have with 3 groups?
Max 2 orthogonal contrasts
What did Bonferroni t-tests reveal about anxiety management in treatments?
Those receiving any treatment had better anxiety management than the control group
What was the significant finding between ACT and CBT?
There was no significant difference between ACT and CBT
In the Dog Jealousy study, what triggered more jealousy?
Any pretend animal triggered more jealousy than jack-o’-lantern
In the Diet and Mood study, what was found about any diet?
Any diet lowered mood compared to no diet
