ABSTRACT

In Chapter 6, we showed how three-level designs are inherently inefficient due to the low volume of information generated at a relatively high cost. There are some modifications that can be made to the basic three-level designs that can make them efficient by producing the required information at a low cost. The 32 design with its three levels and only two factors fits into this category as we showed in Chapter 6. We also showed that for three-level designs with more than two factors, the efficiency degraded rapidly. The solution to this problem was to use the central composite design, which has five levels.