Data Set 13-7: a Political Scientist Reported a Study on Attitudes

Multiple Choice

Data Set 13-7: A political scientist reported a study on attitudes toward increasing military expenditures. The attitudes of four groups were reported: US Army officers, corporate managers, public school teachers, and assembly-line workers. Within each of the categories, those under age 35 were tabulated separately from those over 35. A factorial ANOVA on the data produced a significant interaction; the main effect for age was not significant.
-The degrees of freedom for the interaction mean square in Data Set 13-7 is

A) 1
B) 3
C) 6