A marketing researcher wants to test the hypothesis that, in the population, there is no difference in the importance attached to shopping by consumers living in the northern, southern, eastern, and western United States. A study is conducted and analysis of variance is used to analyze the data. The results obtained are presented in the following table.

Source df Sum of Squares Mean Squares F Ratio F

Probability Between groups 3 70.212 23.404 1.12 0.3 Within groups 996 20812.416 20.896

a. Is there sufficient evidence to reject the null hypothesis?

b. What conclusion can be drawn from the table?

c. If the average importance were computed for each group, would you expect the sample means to be similar or different?

d. What was the total sample size in this study?