Week 5 - Lecture 5

Question 1

What does ANOVA stand for?

Answer 1

Analysis of Variance

Question 2

What does ANOVA test for?

Answer 2

Whether 3 or more group means are significantly different

Question 3

Why can’t we use multiple t-tests for 3+ groups?

Answer 3

It inflates the Type I error rate (false positives)

Question 4

What is the familywise error rate if you do 3 t-tests at α = 0.05?

Answer 4

0.15 or 15%

Question 5

What is a “factor” in ANOVA?

Answer 5

The independent variable (eg. attachment style, type of diet)

Question 6

What are “levels” in ANOVA?

Answer 6

The categories of the factor (e.g. secure, avoidant, anxious

Question 7

What type of data must the dependent variable be?

Answer 7

Quantitative (numeric, e.g. mood scores)

Question 8

What is a between-subjects design?

Answer 8

each group has different participants

Question 9

What does “omnibus test” mean in ANOVA?

Answer 9

ANOVA tells us if a difference exists somewhere, not where

Question 10

What is the F-ratio formula?

Answer 10

F = MS_between / MS_within

Question 11

What does it mean if the F-ratio is greater than 1?

Answer 11

There might be a real difference between the group means

Question 12

What is the “critical F”?

Answer 12

A threshold from the F-distribution table used to decide significance

Question 13

In the jealousy study, what are the IV and DV?

Answer 13

IV = attachment style (secure, avoidant, anxious)
DV = jealousy scores

Question 14

What is the null hypothesis for ANOVA?

Answer 14

All group means are equal:
μ_secure = μ_avoidant = μ_anxious

Question 15

What is the alternative hypothesis for ANOVA?

Answer 15

At least one mean is different:
(μ_k ≠ μ_k′)

Question 16

What does ANOVA partition total variance into?

Answer 16

between-groups variance and within-groups variance

Question 17

What does between-groups variance include?

Answer 17

treatment effect, individual differences, and experimental error

Question 18

What does within-groups variance include?

Answer 18

only individual differences and experimental error (not treatment effect)

Question 19

Why is between-groups variance important?

Answer 19

It’s the only part that can reflect the treatment effect

Question 20

What does it mean if between-groups variance is greater than within-groups variance?

Answer 20

suggests a real treatment effect (F > 1)

Question 21

What is the formula for F-ratio?

Answer 21

F = MS_between ÷ MS_within

Question 22

In the diet and mood study, what was the DV?

Answer 22

Mood score on a scale from 1 to 16

Question 23

How many conditions were in the diet and mood study?

Answer 23

Three: restrict fat, restrict carbs, no restrictions

Question 24

What does SS_Total measure?

Answer 24

Total variability in all participants’ scores from the grand mean

Question 25

What does What does SS_Treat measure?

Answer 25

How much group means differ from the grand mean (between-groups variance)

Question 26

What does SS_Treat measure?

Answer 26

How much group means differ from the grand mean (between-groups variance)

Question 27

What does SS_Error measure?

Answer 27

How much each individual score differs from its own group mean (within-groups variance)

Question 28

What is the shortcut formula for SS_Error?

Answer 28

SS_Error = SS_Total − SS_Treat

Question 29

What is the formula for df_Total?

Answer 29

N-1

Question 30

What is the formula for df_Treat?

Answer 30

k − 1 (where k = number of groups)

Question 31

What is the formula for df_Error?

Answer 31

N - k

Question 32

What does the "treatment" row in a summary table represent?

Answer 32

Variability explained by the independent variable (eg. diet, condition)

Question 33

What does the "error" row represent?

Answer 33

variability within groups due to individual differences and error

Question 34

How do you calculate Mean Square (MS)?

Answer 34

MS = SS ÷ df (Sum of Squares divided by degrees of freedom)

Question 35

How is the F-ratio calculated?

Answer 35

F = MS_treatment ÷ MS_error

Question 36

In the diet study, what was the F_obt value? What was the critical F-value in the diet study (df = 2, 27)? Was the null hypothesis rejected in the diet study? Why?

Answer 36

- 8.603 - 3.37 - Yes, because 8.603 > 3.37, the result was significant.

Question 37

What did the diet study conclude?

Answer 37

Mood significantly varied with diet, F(2, 27) = 8.60, p < .05

Question 38

What was the F_obt in the dog jealousy study? What was the F_crit for the dog jealousy study (df = 2, 15)? Was the null hypothesis rejected in the dog study?

Answer 38

- 5.836 - 3.68 - Yes, because 5.836 > 3.68

Question 39

What did the dog jealousy study find?

Answer 39

Jealousy behaviours varied significantly by interaction condition, F(2, 15) = 5.84, p < .05

Question 40

What type of test is ANOVA?

Answer 40

An omnibus test - it checks if any means differ, not which ones

Question 41

What follow-up tests help find where group differences lie?

Answer 41

Post hoc tests (e.g., Scheffé, Tukey) or planned contrasts.