ABSTRACT
Every process contains at least one performance characteristic. We consider the case of a single performance characteristic, usually denoted by Y. For example, characteristics can be the yield of a process, the thickness of a turbine blade, the strength of a new material, the lifetime of a battery, the life of a machine tool, a circuit board etching, eye focus time, the amount of shrinkage in a molded part, a chemical yield, or the coating thickness of a silicon wafer. The new philosophy of quality advocated by Taguchi states that a good product must be on target and must have minimum deviation from the target. Consequently, we should focus our interest on two parameters, the location parameter and the variation parameter. For instance, let us consider the following experiment. Consider an investigation into the effect of theExample 3.1: concentration of a reactant and the amount of a catalyst on the conversion (yield) in a chemical process. Let the reactant concentration be factor A, and the two levels of interest be 15% and 25%. The catalyst is factor B, with the high level denoting the use of two bags and the low level denoting the use of only one bag. The experiment is replicated three times.
