A social psychologist compares three kinds of propaganda messages on college students’ attitudes toward the war on terrorism. Ninety ( N = 90) students are randomly assigned in equal numbers to the three different communication conditions. A paper-and-pencil attitude measure is used to assess students’ attitudes toward the war after they are exposed to the propaganda statements. An ANOVA is carried out to determine the effect of the three messages on student attitudes. Here is the ANOVA Summary Table:

A. Is the result statistically significant? Why or why not?

B. What effect size measure can be easily calculated from these results? What is the value of that measure?

C. How could doing comparisons of two means contribute to the interpretation of these results?

D. Although the group means are not provided, it is possible from these data to calculate the width of the confidence interval for the means based on the pooled variance estimate. What is the width of the confi dence interval for the means in this study?

Transcribed Image Text:

Source Communication Error Mean Sum of Squares df Square F Р 180.10 2 90.05 17.87 0.000 438.50 87 5.04