A large department store examined a sample of 18 credit card sales and recorded the amounts charged for each of three types of credit cards: MasterCard,Visa,and Discover. Six MasterCard sales,seven Visa,and five Discover sales were recorded. The store used an ANOVA to test if the mean sales for each credit card were equal. What are the degrees of freedom for the F-statistic?
A)18 in the numerator,3 in the denominator
B)3 in the numerator,18 in the denominator
C)2 in the numerator,15 in the denominator
D)6 in the numerator,15 in the denominator

Question

Quizplus · Accepted Answer

The degrees of freedom for the F-statistic in an ANOVA are calculated as follows: the numerator degrees of freedom are one less than the number of groups (k - 1), and the denominator degrees of freedom are the total number of observations minus the number of groups (N - k). Here, k = 3 (MasterCard, Visa, Discover) and N = 18 (total sales). Thus, numerator degrees of freedom = 3 - 1 = 2, and denominator degrees of freedom = 18 - 3 = 15.

A Large Department Store Examined a Sample of 18 Credit