A Plackett-Burman design was used to study the rheological

Chapter 15, Problem 15.39

(choose chapter or problem)

A Plackett-Burman design was used to study the rheological properties of high-molecular-weight copolymers. Two levels of each of six variables were xed in the experiment. The viscosity of the polymer is the response. The data were analyzed by the Statistics Consulting Center at Virginia Tech for personnel in the Chemical Engineering Department at the University. The variables are as follows: hard block chemistry x1, nitrogen ow rate x2, heat-up time x3, percent compression x4, scans (high and low) x5, percent strain x6. The data are presented here. Obs. x1 x2 x3 x4 x5 x6 y 1 2 3 4 5 6 7 8 9 10 11 12 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 194,700 588,400 7533 514,100 277,300 493,500 8969 18,340 6793 160,400 7008 3637 Build a regression equation relating viscosity to the levels of the six variables. Conduct t-tests for all main eects. Recommend factors that should be retained for future studies and those that should not. Use the residual mean square (5 degrees of freedom) as a measure of experimental error.