*6.9. Grocery retailer. A large, national grocery retailer tracks productivity and costs of its facilities closely. Data below were obtained from a single distribution center for a one-year period. Each data point for each variable represents one week of activity. The variables included are the number of cases shipped (X), the indirect costs of the total labor hours as a percentage (X1). a qualitative predictor called holiday that is coded I if the week has a holiday and otherwise (X3), and the total labor hours (Y). 1 2 3 SO 52 X/1: 305,657 X2: 7.17 0 4264 328,476 6.20 0 4496 317,164 4.61 0 4317 290,455 7.99 0 4499 51 411,750 7.83 0 4186 292,087 7.77 0 4342 a. Prepare separate stem-and-leaf plots for the number of cases shipped X, and the indirect cost of the total hours X/2. Are there any outlying cases present? Are there any gaps in the data? b. The cases are given in consecutive weeks. Prepare a time plot for each predictor variable. What do the plots show? c. Obtain the scatter plot matrix and the correlation matrix. What information do these diag- nostic aids provide here? LA *6.9. Grocery retailer. A large, national grocery retailer tracks productivity and costs of its facilities closely. Data below were obtained from a single distribution center for a one-year period. Each data point for each variable represents one week of activity. The variables included are the number of cases shipped (X), the indirect costs of the total labor hours as a percentage (X1). a qualitative predictor called holiday that is coded I if the week has a holiday and otherwise (X3), and the total labor hours (Y). 1 2 3 SO 52 X/1: 305,657 X2: 7.17 0 4264 328,476 6.20 0 4496 317,164 4.61 0 4317 290,455 7.99 0 4499 51 411,750 7.83 0 4186 292,087 7.77 0 4342 a. Prepare separate stem-and-leaf plots for the number of cases shipped X, and the indirect cost of the total hours X/2. Are there any outlying cases present? Are there any gaps in the data? b. The cases are given in consecutive weeks. Prepare a time plot for each predictor variable. What do the plots show? c. Obtain the scatter plot matrix and the correlation matrix. What information do these diag- nostic aids provide here? LA