Bars of soap are scored for their appearance in a manufacturing operation. These scores are on a 1 - 10 scale, and the higher the score the better. The difference between operator performance and the speed of the manufacturing line are believed to measurably affect the quality of the appearance, The following data were collected on this problem. Appearance Operator Line Speed (sums for 30 bars) 150 255 175 246 200 249 150 260 175 223 2 200 150 265 231 3 3 175 217 200 256
1. Using dummy variables, fit a multiple regression model to these data.
2. Using a = 0.05, determine whether operator differences are important in bar appearance. Us-ing the regression model, demonstrate that the average appearance score for operator number 1 is 250, for operator number 20 is 238, and for operator nmber 3 is 256.
3. Does line speed affect appearance? (Use a = 0.005.)
4. What model would you use to predict appearance.