An experiment to investigate the effects of a new technique for degumming of silk yarn was described in the article “Some Studies in Degumming of Silk with Organic Acids” (J. Society of Dyers and Colourists, 1992: 79–86). One response variable of interest was y
weight loss (%). The experimenters made observations on weight loss for various values of three independent variables: x1
temperature (°C)
90, 100, 110;

x2
time of treatment (min)
30, 75, 120; x3
tartaric acid concentration (g/L)
0, 8,