Ribbon bar. Select the Statistics tab. In the Advanced/Multivariate group, click Advanced Models, and from the menu, select Variance Components to display the Variance Components & Mixed Model ANOVA Startup Panel.

Classic menus. On the Statistics - Advanced Linear/Nonlinear Models submenu, select Variance Components to display the Variance Components & Mixed Model ANOVA Startup Panel.

The Startup Panel contains three tabs: Quick, Advanced and Model. Use the options on these tabs to specify the variables for the analysis, the coding and sorting of the levels of the independent variables, and the model for the analysis.

OK. Click the OK button to display the Variance Components and Mixed Model ANOVA/ANCOVA Results dialog box (or the standard variable selection dialog box if you have not already specified variables).

Cancel. Click the Cancel button to close the Startup Panel without performing an analysis.

Options. See Options Menu for descriptions of the commands on this menu.

Open Data. Click the Open Data button to display the Select Data Source dialog box, which is used to choose the spreadsheet on which to perform the analysis. The Select Data Source dialog box contains a list of the spreadsheets that are currently active.

Select Cases. Click the Select Cases button to display the Analysis/Graph Case Selection Conditions dialog box, which is used to create conditions for which cases will be included (or excluded) in the current analysis. More information is available in the case selection conditions overview, syntax summary, and dialog box description.

W. Click the W (Weight) button to display the Analysis/Graph Case Weights dialog box, which is used to adjust the contribution of individual cases to the outcome of the current analysis by "weighting" those cases in proportion to the values of a selected variable.

Weighted moments. Select the Weighted moments check box to specify that each observation contributes the weighting variable's value for that observation. The weight values need not be integers. This module can use fractional case weights in most computations. Some other modules use case weights as integer case multipliers or frequency values. This option is available only after you have defined a weight variable via the W option described above.

DF = W-1 / N-1. When the Weighted moments check box is selected, moment statistics (e.g., mean, variance) can be based on the sum of the weight values for the weighting variable (W-1), or on the number of (unweighted) observations (N-1). The sums of squares and cross products will always be based on the weighted values of the respective observations. However, in computations requiring the degrees of freedom (e.g., standard deviation, t-test, etc.), the value for the degrees of freedom can either be computed as the sum of the weight values minus one, or as the number of observations minus one. Moment statistics are based on the sum of the weight values for the weighting variable if the W-1 option button is selected, and are based on the number of (unweighted) observations if the N-1 option button is selected. For more information on options for using integer case weights, see also Selecting a Weighting Variable.

For more information on methods for estimating variance components, see the Introductory Overview; for examples of mixed model analyses in which variance components are estimated, see the Examples. For basic information about ANOVA in linear models, refer to Elementary Statistical Concepts. See also, the Variance Components Index.