Question

How does gender and occupational prestige affect credibility? Graduate students in a public health program are asked to rate the strength of a paper about the health risks of childhood obesity. In reality, all student raters are given the same paper, but the name and degree associated with the author are changed. The student raters are randomly assigned to one group from the following name ("John Lake", "Joan Lake") and degree (M.D., R.N., Ph.D.) combination. The raters score the paper from 1 to 5 on clarity, strength of argument, and thoroughness. The total scores (the sum of the three scores) are given in the table below. What can be concluded with an α of 0.01?

John Lake / M.D.	John Lake / R.N.	John Lake / Ph.D.	Joan Lake / M.D.	Joan Lake / R.N.	Joan Lake / Ph.D.
12 15 16 15 14	15 16 12 13 13	10 8 13 12 9	15 10 12 14 12	10 7 8 10 6	11 11 12 8 8

a) What is the appropriate test statistic?
---Select--- na one-way ANOVA within-subjects ANOVA two-way ANOVA

b) Compute the appropriate test statistic(s) to make a decision about H₀.
Name: p-value =  ; Decision:  ---Select--- Reject H0 Fail to reject H0
Degree: p-value =  ; Decision:  ---Select--- Reject H0 Fail to reject H0
Interaction: p-value =  ; Decision:  ---Select--- Reject H0 Fail to reject H0


c) Compute the corresponding effect size(s) and indicate magnitude(s).
Name: η² =  ;  ---Select--- na trivial effect small effect medium effect large effect
Degree: η² =  ;  ---Select--- na trivial effect small effect medium effect large effect
Interaction: η² =  ;  ---Select--- na trivial effect small effect medium effect large effect


d) Make an interpretation based on the results.

There is a name difference in the total scores.There is no name difference in the total scores.    

There is a degree difference in the total scores.There is no degree difference in the total scores.    

There is a name by degree interaction in the total scores.There is no name by degree interaction in the total scores.    

Answer 1

Two-way ANOVA: Score versus Name, Degree

Source	DF	SS	MS	F	P
Name	1	50.70	50.70	15.36	0.001
Degree	2	59.27	29.63	8.98	0.001
Interaction	2	36.20	18.10	5.48	0.011
Error	24	79.20	3.30
Total	29	225.37

S = 1.817 R-Sq = 64.86% R-Sq(adj) = 57.54%

a) What is the appropriate test statistic?
Ans: Two-way ANOVA

b) Compute the appropriate test statistic(s) to make a decision about H₀.
Name: p-value = 0.001 ; Decision: Reject H0
Degree: p-value = 0.001 ; Decision:  Reject H0
Interaction: p-value = 0.011; Decision: Fail to reject H0


c) Compute the corresponding effect size(s) and indicate magnitude(s).
Name: η² = 50.70/225.37=0.0.2250; large effect
Degree: η² =  59.27/225.37=0.2630; large effect
Interaction: η² =36.20/225.37= 0.0.1606 ; large effect


d) Make an interpretation based on the results.

There is a name difference in the total scores.

There is a degree difference in the total scores.

There is no name by degree interaction in the total scores.