Searching for the Optimum Proportions
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The most efficient plan is only the most efficient in the specified search space. Minitab can find the most efficient or "optimum" allocation of test units in two ways:

·    You specify the search space as a finite set or sets of proportions. Each column represents a different test plan. Minitab ranks those test plans according to their efficiency.

·    Minitab searches for the optimum proportions in ranges. That is, Minitab uses a step to go from one candidate group of proportions to another. The default step length is 0.05, but you can increase or reduce the length.