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FIGURE 20-5. A Taguchi experiment flow diagram. Source: Ranjit Roy, A Primer on the Taguchi Method (Dearborn, MI: Society of Manufacturing Engineers, 1990), p. 231. Reproduced by permission.

The Taguchi method is most effective when applied to experiments with multiple factors. But the concept of selecting the proper levels of design factors, and reducing the variation of performance around the optimum/target value, can be easily illustrated through an example.

Consider a baking process. Assume several bakers are given the same ingredients to bake a pound cake, the object being to produce the best-tasting cake. Within limits, they can adjust the amount of ingredients, but they can only use the ingredients provided. They are to make the best cake within available design parameters. Taguchi's approach would be to design an experiment considering all baking ingredients and other influencing factors such as baking temperature, baking time, oven type (if a variable), and so on.

The idea is to combine the factors at appropriate levels, each within the respective acceptable range, to produce the best result and yet exhibit minimum variation around the optimum result. Our objective is to determine the right proportions of the five major ingredients—eggs, butter, milk, flour, and sugar—so that the recipe will produce the best cake most of the time. Based on past experience, the working ranges of these factors are established at the levels shown in Figure 20-4. At this point we face the following questions. How do we determine the right combination? How many experiments do we need to run and in what combination? Figure 20-5 shows a Taguchi experiment flow diagram.

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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