Chemical shipment. The data to follow, taken on 20 incoming shipments of chemicals in drums arriving at a warehouse, show number of drums in shipment (XI), total weight of shipment (X2), in hundred pounds), and number of minutes required to handle shipment (Y).
Given below are the estimated ridge standardized regression coefficients, the variance inflation factors, and R2 for selected biasing constants c.
a. Fit regression model (6.1) to the data and find the fitted values.
b. Make a ridge trace plot for the given c values. Do the ridge regression coefficients exhibit substantial changes near c = O?
c. Why are the (VIF)1 values the same as the (VIF)2 values here?
d. Suggest a reasonable value for the biasing constant c based on the ridge trace, the VlF values, and R2.
e. Transform the estimated standardized regression coefficients selected in part (c) back to the original variables and obtain the fitted values for the 20 cases. How similar are these fitted values to those obtained with the ordinary least squares fit in part (a)?