Answer Happy

The bookstore data concerns weekly sales at Pages Bookstore (Sales), Pages weekly advertising expenditure (Adver), and the weekly advertising expenditure of Pages main competitor (Compadv). Here, the sales values are expressed in thousands of dollars, and the advertising expenditure values are expressed in hundreds of dollars. [Download the Pages Bookstore Dataset here.] In an excel spreadsheet, estimate a simple linear regression that relates sales (y) with Pages advertising (x1) expenditure. y = bo + bixi tr Obtain the normal probability plot and residual plot from the simple linear regression model. Comment on the model assumptions by conducting a residual analysis. Are all the regression model assumptions satisfied? (a) Comment on mean zero assumption. (b) Comment on constant variance assumption. (c) Comment on independence assumption. (d) Comment on normality assumption.

Adver 18 20 20 25 28 29 29 28 30 31 34 35 36 38 41 45 Compadv 10 10 15 15 15 20 20 25 35 35 35 30 30 25 20 20 Sales 22 27 23 31 45 47 45 42 37 39 45 52 57 62 73 84