A commercial real estate company evaluates vacancy rates, square footage, rental rates, and operating expenses for commercial properties in a large metropolitan area in order to provide clients with quantitative information upon which to make rental decisions. The data are taken from 81 suburban commercial properties that are the newest, best located, most attractive, and expensive for ¯ve speci¯c geographical areas. The variables are : rental rates (Y), the age (X1), operating expenses and taxes (X2), vacancy rates (X3), and total square footage (X4) (columns in the data file are in that order). (a) Obtain the scatter plot matrix and the correlation matrix. Interpret these and state your principal findings.