Factorial ANOVA

Question 1

What is the main limitation of t-tests?

Answer 1

Only compares two means. Have to conduct more than one t-test. Increases family wise error/Type I error.

Question 2

What are the main advantages of ANOVA?

Answer 2

Can compare lots of conditions at once.
Decreases chances of false positives.
Can be used with more than one IV + can see how they interact.

Question 3

What is the main ANOVA rationale?

Answer 3

Systematic + unsystematic variation. Want to see how much overall variation is systematic vs unsystematic.
We want systematic to be larger than unsystematic.

Question 4

What is the difference between within-group and between-groups variation?

Answer 4

Within-groups - not due to our manipulation.

Between-groups - our manipulation + random effects.

Question 5

How do we know if our experimental manipulation has had an effect?

Answer 5

Between-groups > within-groups.

Question 6

How do we calculate the effect of our manipulation in an independent ANOVA?

Answer 6

between-groups variance / within-groups variance.

Question 7

What are the 2 main assumptions for an independent ANOVA?

Answer 7

Parametric test!
Normal distribution.
Interval/ratio level data.

Question 8

Is normality more of a problem for one-tailed or two-tailed tests?

Answer 8

One-tailed.

Question 9

What is a unique assumption for independent ANOVAs?

Answer 9

Homogeneity of variance.

Levene’s test.

Question 10

What is a unique assumption for repeated measures ANOVAs?

Answer 10

Sphericity.
Mauchly’s test.
Variances of differences between conditions are similar.

Question 11

When is homogeneity of a variance less of a problem?

Answer 11

When group sizes are equal.

Question 12

What are the two main tests that can be used if homogeneity of variance is violated?

Answer 12

Brown-Forsythe.

Welch’s F.

Question 13

Should Levene’s test and Mauchly’s test be significant or non-significant for the assumptions to be met?

Answer 13

Non-significant.

Question 14

When do we use post-hoc tests?

Answer 14

When we have no specific hypothesis.

Use Bonferroni.

Question 15

What are the main conservative post-hoc tests?

Answer 15

Bonferroni.

Scheffe.

Question 16

What is the main less conservative post-hoc test?

Answer 16

Turkey HSD.

Question 17

What post-hoc test do we use when equal variances cannot be assumed?

Answer 17

Games-Howell.

Question 18

What does a more conservative post-hoc test mean?

Answer 18

Less chance of Type I error.

Higher chance of Type II error.

Question 19

What should you report for post-hoc tests?

Answer 19

P-value + look at means for direction of effect.

Question 20

What is a factorial ANOVA?

Answer 20

ANOVA with 2+ IVs.

Question 21

How do you calculate the number of interactions?

Answer 21

2(to the power of)k - k - 1.

Where k is the number of IVs.

Question 22

What is an additional interpretation we must make when conducting a factorial ANOVA?

Answer 22

We must look at the interaction graph.

Question 23

What is a 2x3x3 design?

Answer 23

Three IVs; 1st has 2 levels, 2nd and 3rd have 3 levels.

Question 24

What is the best way to report an ANOVA (give an example)?

Answer 24

(For a 2x3 design): 
A 2(Gender: male vs female) x 3(Dosage: low, medium and high) independent design.

Question 25

What effect size is used for a two-way repeated measures ANOVA?

Answer 25

Partial eta-squared.

Question 26

When do we use planned comparisons?

Answer 26

When we have a hypothesis.

Question 27

What statistics can we use if Mauchly’s test is violated?

Answer 27

Greenhouse-Geisser or Huynh-Feldt.

Question 28

What statistics do we report for planned comparisons?

Answer 28

F, df, p, np-squared.

Question 29

When is there a significant interaction in the interaction graph?

Answer 29

When the lines are crossing/non-parallel.

If the lines don’t cross then the relationship is non-significant.

Question 30

What is the interaction graph named?

Answer 30

The means plot.