=+66. The accompanying data was taken from the article

“Applying Stepwise Multiple Regression Analysis to the Reaction of Formaldehyde with Cotton Cellulose” (Textile Research J., 1984: 157–165). The dependent variable is durable press rating, a quantitative measure of wrinkle resistance, and the four independent variables are formaldehyde concentration, catalyst ratio, curing temperature, and curing time, respectively.