Noncentrality Interval Estimation and the Evaluation of Statistical Models

Select the Quick tab of the Planned Contrast: Interval Estimation dialog box to access options to implement the procedure (Steiger & Fouladi, 1997) for computing a confidence interval for Es, the standardized effect size.

Observed t. In the Observed t box, enter the observed value of the t-statistic.

No.
of Groups. In the No. of Groups
box, enter the number of independent samples on which the analysis is
based.

N per Group. In the N per Group box, enter the sample size per group.

Conf. Level. In the Conf. Level box, enter the confidence level for the confidence interval calculation. Note the spreadsheet gives the upper and lower limits for Es.

SS Weights. In the SS Weights box, enter the sum of the squares of the contrast weights used in computing the contrast being tested. You can enter this value directly in this field, or click Enter Weights to request the program to calculate it.

Enter Weights. Click the Enter Weights button to display the Planned Contrast: Effects Calculation dialog box. Use this dialog box to have STATISTICA calculate the sum of squares of the contrasts weights (needed for the sample size calculation).