Tests

Question 1

For what post hoc tests are used for?

Answer 1

Main effects significant.
Used to determine which pairs of means are significantly different from one another.

Question 2

Cite 2 post hoc tests

Answer 2

Sheffé & Tukey’s Honestly Significant Difference (HSD) test

Question 3

Which one is the most conservative between Sheffé & Tukey’s Honestly Significant Difference (HSD) test?

Answer 3

Sheffé

Question 4

Pros of Sheffé’s test

Answer 4

Pros:
- Can be used if groups have different sample sizes
- Less sensitive to departures from the assumption of normality and equal variances in the population
- Most conservative test

Question 5

Cons of Sheffé’s test

Answer 5

Has lower power to detect differences

Question 6

How does the Sheffé’s test work?

Answer 6

Compared Fcomparison (that you calculated) with F crit x (k-1)

Question 7

When is the Tukey’s HSD test used?

Answer 7

If groups have equal sample sizes.

Question 8

What test used the studentized range statistic, Q?

Answer 8

Tukey’s HSD

Question 9

How does Tukey’s HSD work?

Answer 9

Calculate observed Q and Q crit (N-k). Compare the two.

Question 10

What is the H0 in Tukey’s HSD?

Answer 10

H0 : μg = μg′

Question 11

HSD

Answer 11

Minimum absolute difference between two means required for a statistically significant difference.

Question 12

What post hoc test do you use when sample sized are unequal?

Answer 12

Tukey-Kramer test

Question 13

When do you use simple main effects?

Answer 13

When interaction significant

Question 14

What follow up analysis do you do if:
Interaction significant BUT at least 1 of the main effect is.

Answer 14

Post hoc testing. Comparison of marginal means of each factor.

Question 15

What follow up analysis do you do if:
Interaction significant BUT dominated by main effect.

Answer 15

Understand main effect first and then evaluate how it changes at the levels of other factor.

Question 16

What follow up analysis do you do if:
Interaction significant & dominates main effect.

Answer 16

Simple main effects.

Question 17

What are the heuristics to choose which factor you’re using in a simple main effect? (4)

Answer 17

1) Factor that has the highest number of levels
2) Quantitative factor
3) Factor with the greatest SS for main effect
4) Experimentally manipulated factor

Question 18

When do you do simple comparisons?

Answer 18

Follow-up analyses for significant Simple main effects.
Comparisons among means of the factor for which we identified a significant main effect.

Question 19

What is a recommendation for simple main effects and simple comparisons?

Answer 19

Set family wise Type 1 error to 0.10.
Adjust Type 1 error.

Question 20

When do you need to adjust the alpha family wise? (for main effects)

Answer 20

When only main effects are significant.

Question 21

Which test correct alpha family wise (main effects)?

Answer 21

Bonferroni’s correction

Question 22

What is Bonferroni’s correction? (calculation)

Answer 22

apha(FW) = alpha(FW) / number of post hoc comparisons (e.g. 3 if 3 levels)

Question 23

Controlling Type 1 error when conducing follow-up analyses for significant MAIN EFFECTS.

Answer 23

Bonferroni’s correction

Question 24

Controlling Type 1 error when conducting follow-up analyses for significant INTERACTIONS

Answer 24

The recommendation in Keppel and Wickens is to set αF W = 0.10 for the set of simple main effects because these effects incorporate variation due to both the main effect of the factor for which we are computing simple main effects and the interaction.

Question 25

Two types of planned comparisons

Answer 25

Orthogonal (independent) and non-orthogonal (dependent).

Question 26

When do you do planned comparisons?

Answer 26

Designed before data is collected. Specific hypotheses.