# Question

The owner of a rapidly growing computer store tried to explain the increase in biweekly sales of computer software, using four explanatory variables: number of titles displayed, display footage, current customer base of Windows- based computers, and current customer base of Mac computers. The data are given below for the 52 biweekly sales periods as follows: biweek, soft-ware sales, number of titles displayed, display footage, Windows- based customers, and Mac based customers.

a. Before doing the calculations, consider the economics of the situation, and state what sign you would expect for each of the partial slopes.

b. Obtain a multiple regression equation with sales as the dependent variable and all other variables as independent. Does each partial slope have the sign you expected in part (a)?

c. Calculate a 95% confidence interval for the coefficient of the titles variable. The computer output should contain the calculated standard error for this coefficient. Does the interval include 0 as a plausible value?

a. Before doing the calculations, consider the economics of the situation, and state what sign you would expect for each of the partial slopes.

b. Obtain a multiple regression equation with sales as the dependent variable and all other variables as independent. Does each partial slope have the sign you expected in part (a)?

c. Calculate a 95% confidence interval for the coefficient of the titles variable. The computer output should contain the calculated standard error for this coefficient. Does the interval include 0 as a plausible value?

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