When we analyze data for the census tracts in the greater Los Angeles area, we find no significant correlation between median tax bill and median lot size. Yet a considerable positive correlation occurs when we control for the percentage of the tract used for business. Explain how the percentage of the tract used for businesses could be a suppressor variable if it is positively correlated with median tax bill and negatively correlated with median lot size.

(2)Statistical interactions.Agresti & Finlay p. 316, problem 10.22 (7.5 points)

For lower-level managerial employees of a fast-food chain, the prediction equation relating Y = annual income (thousands of dollars) to = number of years experience on the job equals = 14.2 + 1.1for males and = 14.2 + 0.4for females. Explain how these equations show evidence of statistical interaction.