A large, national grocery retailer tracks the productivity and costs of its facilities closely. Data below were obtained from a single distribution center for one year. Each data point for each variable represents one week of activity. The variables included are the total labor hours (LabHours, Y), the number of cases shipped (Cases, in thousands, X₁), the indirect costs of the total labor hours as a percentage (Indirect%, X₂), a qualitative predictor called holiday that is coded as 1 if the week has a holiday and 0 otherwise (Holiday, X₃). The first 10 if the n = 54 cases are shown below, along with some multiple regression output: