The Power Details window and reports are the same as those in the general fitting platform launched by the Fit Model platform. For more details about power calculation, see Power Calculations in the Fitting Linear Models book.
For each of four columns Alpha, Sigma, Delta, and Number, fill in a single value, two values, or the start, stop, and increment for a sequence of values. See Example of the Power Details Window. Power calculations are performed on all possible combinations of the values that you specify.
Alpha (α)
Significance level, between 0 and 1 (usually 0.05, 0.01, or 0.10). Initially, a value of 0.05 shows.
Sigma (σ)
Delta (δ)
Raw effect size. For details about effect size computations, see Effect Size in the Fitting Linear Models book. The first position is initially set to the square root of the sums of squares for the hypothesis divided by the square root of n; that is, .
Number (n)
Total sample size across all groups. Initially, the actual sample size is put in the first position.
Solves for the power (the probability of a significant result) as a function of all four values: α, σ, δ, and n.
Solves for the value of the parameter or linear test that produces a pvalue of α. This is a function of α, σ, n, and the standard error of the estimate. This feature is available only when the X factor has two levels and is usually used for individual parameters.
Adjusted power and confidence limits are computed only for the original Delta, because that is where the random variation is.
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