One Variance: Power Calculation Parameters - Quick Tab

Select the Quick tab of the One Variance: Power Calculation Parameters dialog box to access options to establish the basic parameters for analyzing power for the chi-square test on one variance.

Fixed Parameters

The entries in the boxes under Fixed Parameters establish the fixed, or baseline, parameters for subsequent power calculations and graphs. Parameters that are not varied explicitly as the dependent (X-axis) variables in a graphical analysis will be set equal to these values.

Var

In the Var box, enter the population variance assumed to hold in the population being tested.

Var0

In the Var0 box, enter the null hypothesized variance.

Df

In the Df box, enter the number of degrees of freedom for the analysis.  If the hypothesis test is based on a single group, this value is N - 1.  However, the single variance test can be based on more than one independent sample being used to estimate the same population variance.  In that case, the degrees of freedom are N_tot - J, where N_tot is the total of all the sample sizes, and J is the number of groups.

Alpha

In the Alpha box, enter the type I error rate (a) used in determining the critical value for the chi-square statistic.

Type of Hypothesis

The choice of option buttons under Type of Hypothesis determines the type of null hypothesis tested by the chi-square statistic.

2-tailed (Var = Var0)

Select the 2-tailed (Var = Var0) option button to use a null and alternative  hypotheses of the form

H₀: σ² = σ²₀    H₁: σ² ¹ s²₀

1-tailed (Var <= Var0)

Select the 1-tailed (Var <= Var0) option button to use a null and alternative  hypotheses of the form

H₀: σ² ≤ σ²₀    H₁: σ² > σ²₀

1-tailed (Var >= Var0)

Select the 1-tailed (Var >= Var0) option button to use a null and alternative  hypotheses of the form

H₀: σ² ≥ σ²₀    H₁: σ² < σ²₀