A Plackett-Burman design is used for the purpose of studying the rheological properties of high molecular-weight, copolymers. Two levels of each of six variables are fixed in the experiment. The viscosity of the polymer is the response. The data were analyzed by the Statistics Consulting Center at Virginia Polytechnic Institute and State University for personnel in the Chemical Engineering Department at the University. The variables are as follows: hard block chemistry x1, nitrogen flow rate x2, heat-up time x3, percent compression x4, scans high and low x5, percent strain x6. The data are presented here. Build a regression equation relating viscosity to the levels of the six variables. Conduct f-tests for all main effects. 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 experimentalerror.

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Obs. *1 1 -1 1 -: 194, 700 1 588, 400 1 - 1 -1 -1 - 1 2 7,533 1 514, 100 -1 277, 300 1 493, 500 8,969 3 -1 -1 1 -1 -1 -1 -1 18, 340 6,793 160,400 7,008 3,637 -1 - 1 - 1 - 1 - 1 9. 10 1 1 - 1 12 - 1 -1 -1 - 1 - 1 -1 - 1 - 1 -1 - 1 - 1 -1