Analysis of a Central Composite (Response Surface) Experiment

Analyzing Central Composite Designs

Click the OK button in the Design & Analysis of Central Composite (Response Surface) Experiments dialog box to display the Analysis of a Central Composite (Response Surface) Experiment dialog box (if you have chosen to analyze a design via the Analyze design tab). This dialog box contains nine tabs: Quick, Model, Design, ANOVA/Effects, Means, Review/save residuals, Residual plots, Box-Cox, and Prediction & profiling. Use these tabs to access options to analyze the design as well as options for displaying the different aspects of the design.

Summary box:

The Summary box displays a summary of the design including the number of factors, runs, blocks (if applicable), and replications.

Copy button: Click the Copy button to copy either the selected text (if text has been selected) in the Summary box or all of the text (if no text has been selected) to the Clipboard. Note that the copied text retains formatting information (such as font, color, etc.).

Contract/Expand button: Click the Contract/Expand button to contract or expand the Summary box. When contracted, you can see only one line of the Summary box text and can scroll through the text using a scroll bar. Note that when contracted, the text is scrolled so that the first non-blank line is at the top. When expanded (the default setting), the entire Summary box will be displayed in the Results dialog box.

Variable:

If multiple dependent variables are specified for the analysis, use the Variable box to select the dependent variable for which to review the results.

Print results:

Click the Print results button to compute the main effects and interactions estimates, the regression coefficients, and the ANOVA table for the current variable and send them to a report. Note that if you don't have a Send to report option selected in the Output Manager, you will be prompted to select that option here. To send the results to a printer, see printing a report.

All variables:

Select the All variables check box to send the results for all dependent variables in the current analysis to a report. See also, Note on Missing Data and Multiple Dependent Variables and Note on Unbalanced Designs and Singular Effects Matrices.

Summary:

Click the Summary button to produce a spreadsheet with the ANOVA effect estimates and coefficients of the model for the rescaled factor values (see Review/set factor names and settings on the Design tab). The effects that are computed depend on the current model, as specified via the options in the Include in model group box on the Model tab. If an error term for the ANOVA is available, this spreadsheet also includes the standard errors of the parameter estimates and coefficients, their confidence intervals (according to the value in the Confidence interval box on the ANOVA/Effects tab), and their statistical significance. Statistically significant parameters are highlighted in the spreadsheet; the criterion for statistical significance can be set via the Alpha (highlighting) option on the ANOVA/Effects tab (the default Alpha is .05). If the Effects sorted by size check box on the ANOVA/Effects tab is selected, the estimates in the spreadsheet are sorted by their absolute size (except for the intercept, which is always listed first). For more information on the spreadsheet, see Main Effects and Interactions Spreadsheet for Central Composite Experiments.

Cancel:

Click the Cancel button to return to the Design & Analysis of Central Composite (Response Surface) Experiments dialog box.

Options:

Click the Options button to display the Options menu.