Select the Quick tab of the Planned Contrast: Sample Size Parameters dialog box to access options to establish the basic parameters for analyzing sample size for the planned contrast.

Fixed Parameters. The entries in the boxes under Fixed Parameters establish the values for the fixed parameters in the power calculation.

Alpha. In the Alpha box, enter the Type I error rate used in determining the critical value for the t-statistic.

Power Goal. In the Power Goal box, enter the minimum acceptable power, for which a minimum sample size is calculated. If the search for an acceptable sample size is successful, the actual power of the statistical test will be greater than or equal to this value.

Es. In the Es box, enter the standardized effect. Note that you can click the Calculate Es button to have STATISTICA calculate it from cell means and contrast weights.

No. of Groups. In the No. of Groups box, enter the number of independent samples on which the analysis is based. This should be the total number of independent samples available that are assumed to have equal standard deviations.

SS Weights. In the SS Weights box, enter the sum of the squares of the contrast weights used in computing the contrast being tested. Note that you can click the Calculate Es button to have STATISTICA calculate it.

Calculate Es. Click the Calculate Es button to display the Planned Contrast: Effects Calculation dialog box. Use this dialog box to specify that STATISTICA calculates the sum of squares of the contrasts weights (needed for the sample size calculation) as well as the standardized effect (Es).