GDA Models Results - Cases Tab

Select the Cases tab of the GDA Models Results dialog to access options to compute various classification statistics for each case (observation), including the canonical scores, Mahalanobis distances, posterior classification probabilities, and the actual classifications. These statistics can be computed for the Analysis sample (i.e., for observations from which the current model parameter estimates were computed), the Cross-validation sample (observations not included in the original computations, but with valid data for both the predictor and dependent variable), and the Prediction sample (observations with valid data for the predictor variables but missing data for the dependent variable). See also the GDA Quick Specs Dialog - Advanced tab for how to specify a Cross-validation sample.

Sample.

Analysis, Cross-val., Both, Pred.

Select the respective option button in the Sample group box to specify which type of sample to base the classification statistics. You can compute classification statistics and canonical scores for all observations that were used to compute the current results (select Analysis), all observations that were not used to compute the current results, but have valid data for all predictors and the dependent variable (select Cross-val(idation)), both the Analysis and Cross-validation samples (select Both), or compute classification statistics and canonical scores for all cases that have valid data for the predictor variables, but missing data for the dependent variable (select Prediction). If these options are dimmed, no valid cases in the prediction sample were found, and/or no cross-validation sample was specified via the GDA Quick Specs Dialog - Advanced tab, or via the SAMPLE keyword in the GDA Models Syntax Editor dialog.

Sample classification matrix

Click the Sample classification matrix button to display a spreadsheet containing the classification matrix. The classification matrix contains information about the number and percent of correctly classified cases in each class (group). The Sample (cases or observations) that will be included in the computation of the classification matrix depends on the setting of the respective SAMPLE option (see above).

Display prior probabilities

Click the Display prior probabilities button to display a results spreadsheet containing the currently specified a priori classification probabilities. Refer to the Discriminant Analysis module for a discussion of prior classification probabilities, and how they affect the classification of cases. Options for specifying the prior classification probabilities are provided on the GDA Quick Specs Dialog - Advanced tab, and via the PRIORS keyword, using GDA syntax.

Case statistics to compute

Use the Case statistics to compute group box to determine the statistics that are computed (for each case), when you click the Display statistics or the Save statistics button. These statistics are discussed in the context of the Discriminant Analysis and Canonical Analysis modules in the topics on Classification and Canonical Analysis.

Display statistics

Click the Display statistics button to display a results spreadsheet containing the selected Case statistics to compute.

Save statistics

Click the Save statistics button to display the standard variable selection dialog, which is used to select the variable(s) you want to display together with the selected Case statistics to compute. After you select the variable(s), a spreadsheet containing the specified variable(s) along with numerous case statistics will be displayed in an individual window (regardless of the settings in the Options - Output Manager tab or the Analysis/Graph Output Manager dialog). You can, however, add the spreadsheet to a workbook or report using the

buttons, respectively. Note that in order to save the spreadsheet, you must select the spreadsheet and select Save or Save As from the File menu. This is useful if you want to use the case statistics for further analyses with other Statistica analyses.