A discount retailer recently began selling grocery items in its 64 stores located in the Midwest To see how advertising affects the sales of these new items, it varied the number of pages showing...

A discount retailer recently began selling grocery items in its 64 stores located in the Midwest To see how advertising affects the sales of these new items, it varied the number of pages showing grocery items in the advertising circular that it distributes to shoppers in neighboring areas. The circular is given away in local newspapers and online. Figure 8 graphs the average daily sales of grocery items versus the number of pages devoted to grocery items.

a. Explain why these data do not satisfy the linear condition. What plot would probably show the nonlinear pattern more clearly?¹

b. Which change in advertising pages appears to have the larger effect on sales: increasing from one to two pages, or from four to five?²

c. Sketch a bending pattern that captures the relationship between advertising pages and grocery sales better than the fitted line.³

d. What sort of transformations does the bulging rule (Figure 5) suggest would capture the pattern between pages and sales?⁴