3: One-Way ANOVA

Question 1

When is an ANOVA used?

Answer 1

When the IV has more than 2 levels.

Question 2

How is an ANOVA an extension of the t-test?

Answer 2

F = t^2

Question 3

Why do we use ANOVAs?

Answer 3

Reduces the rate of type I error.

Question 4

Familywise error rate

Answer 4

The probability that at least one in a ‘family’ of comparisons will result in type I error.

Question 5

How do we calculate familywise error?

Answer 5

a’ = 1 - (1 - a)^c. (1 - a) = Level of confidence. c = Number of comparisons.

Question 6

Assumptions of ANOVA

Answer 6

Normality, homogeneity of variance, sample size, independence of observations.

Question 7

What are Levene’s and Welch’s?

Answer 7

Levene’s tests for homogeneity of variance, Welch’s F corrects for this.

Question 8

Variance between IV levels

Answer 8

Treatment effects, individual differences, and experimental error (random/constant).

Question 9

Variance within IV levels

Answer 9

Individual differences and experimental error (random).

Question 10

Model Sum of Squares (SSM)

Answer 10

Sum of squared differences between individual values and the grand mean - between IV level variance.

Question 11

Residual Sum of Squares (SSR)

Answer 11

Sum of squared differences between individual values and corresponding IV level mean - within IV level variance.

Question 12

How is SST calculated?

Answer 12

SSM + SSR

Question 13

dfM =

Answer 13

k (number of IV levels) - 1

Question 14

dfR =

Answer 14

N (total sample size) - k (number of IV levels)

Question 15

Model Mean Square (MSM)

Answer 15

SSM
____

dfM

Question 16

Residual Mean Square (MSR)

Answer 16

SSR
____

dfR

Question 17

How can F be calculated?

Answer 17

F = MSM / MSR

Question 18

Which post-hoc test is classed as ‘very conservative’?

Answer 18

Bonferroni (very low type I error risk, very high type II error risk).

Question 19

Which post-hoc test is classed as ‘liberal’?

Answer 19

LSD (high type I error risk, low type II error risk).

Question 20

Which post-hoc test is classed as ‘reasonably conservative’?

Answer 20

Tukey HSD (low type I error risk, high type II error risk).

Question 21

Partial eta-squared

Answer 21

How much variance in the DV can be explained by manipulation of the IV overall.

Question 22

What is a small partial eta-squared score?

Answer 22

< .01

Question 23

What is a medium partial eta-squared score?

Answer 23

.01 - .06

Question 24

What is a large partial eta-squared score?

Answer 24

> .14

Question 25

How is partial eta-squared calculated?

Answer 25

SSM / (SSM + SSR)