Statistical Thinking: Improving Business Performance, Second Edition

APPENDIX E

More on Design of Experiments

Experiment, and it will lead you to the light.

—Cole Porter

Chapter 7 discussed the use of statistically designed experiments to collect data for building models, focusing on experiments involving three variables. As you use this approach, you may encounter situations in which you have four or more variables to study. This appendix presents some designs that enable you to investigate the effects of four or more variables and provides guidance on how to analyze the results. The designs discussed are summarized in Table E.1 and shown in detail in Tables E.2 to E.7. The references at the end of this appendix present further details on the use and analysis of these designs.

TABLE E.1 Some Useful Experimental Designs

TABLE E.2 Two-Level, Four-Factor Factorial Design

TABLE E.3 Two-Level, Five-Factor Factorial Design

TABLE E.4 Two-Level, Five-Factor Fractional-Factorial Design

TABLE E.5 Two-Level Fractional-Factorial Design for 6, 7, or 8 Variables

TABLE E.6 Twelve-Run Plackett-Burman Design

Table E.1 shows the number of variables that each design ...