Use the DOE > Design Diagnostics > Sample Size and Power command to answer the question “How many runs do I need?” The important quantities are sample size, power, and the magnitude of the effect. These depend on the significance level, alpha, of the hypothesis test for the effect and the standard deviation of the noise in the response. You can supply either one or two of the three values. If you supply only one of these values, the result is a plot of the other two. If you supply two values, the third value is computed.

The Sample Size and Power platform can answer the question, “Will I detect the group differences I am looking for, given my proposed sample size, estimate of within-group variance, and alpha level?” In this type of analysis, you must approximate the group means and sample sizes in a data table as well as approximate the within-group standard deviation (σ).