Rayon whiteness is an important factor for scientists dealing in fabric quality. Whiteness is affected by pulp quality and other processing variables. Some of the variables include acid bath temperature, ◦C (x1);

cascade acid concentration, % (x2); water temperature, ◦C (x3); sulfide concentration, % (x4); amount of chlorine bleach, lb/min (x5); and blanket finish temperature, ◦C (x6). A set of data from rayon specimens is given here. The response, y, is the measure of whiteness.