C&RT Quick Specs - Quick Tab
The Quick tab of the C&RT Quick specs dialog box contains options to select the variables and the codes of variables required for the Type of analysis selected on the General Classification and Regression Trees Startup Panel - Quick tab.
- Variables
- Click this button to display a four-variable lists selection dialog box from which you select the dependent variable, count variable (optional), categorical predictor variables, and continuous predictors.
From the first list, select the dependent variable. If you are analyzing a classification problem with a categorical response variable, then the dependent variable must contain text or numeric (integer) codes that identify the class or group to which each case or observation belongs.
From the second list, select the categorical variables (factors). Note that these variables must contain text or numeric codes that identify the classes or groups to which each case or observation belongs.
From the third list, select the continuous predictors.
From the fourth list, select the count variable. This variable is optional. If selected, it will be used as a case-multiplier in the analysis. Thus, by using a count variable you can analyze input data that have previously been aggregated (tabulated).
- Categorical response
- Select this check box to analyze a dependent (criterion) variable that is categorical in nature, i.e., to perform a classification analysis. When this check box is selected, the Response codes button will become active, provided you have specified a dependent variable. Note that if this check box is not selected, even the categorical response variable selected for the analysis will be treated as a continuous response variable. Likewise, if the selected dependent variable is continuous and the Categorical response check box is selected, the dependent variable will be treated as categorical.
- Response codes
- This button is available only if a dependent variable has been specified and the Categorical response check box is selected. In this case, the dependent variable is assumed to be categorical in nature, and the object of the analysis is to correctly classify the cases (observations) into groups specified by the dependent variable. Click the Response codes button to make a selection for the Categorical response from the list of codes for the Dependent variable selected in the current analysis. The list of codes can be displayed by clicking the Zoom button on the Select codes for the categorical response dialog box. Note that you must select at least two codes for the selected Dependent variable.
- Factor codes
- Once you have made the Variables selection, this button will be available. Click the Factor codes button to select codes for the Categorical factors. The list of codes can be displayed by clicking the Zoom button on the Select codes for indep. vars (factors) dialog box. Note that you must select at least two codes for each of the selected Categorical factors.
- Between Effects
- If you choose to perform a Standard C&RT analysis, a box next to the Between effects text will show the current "design," which in this case amounts to a simple combination of the selected predictor variables and the factors (categorical predictors). If you select C&RT with coded design from the Startup Panel, then you can specify an ANOVA/ANCOVA-like design for the selected predictor variables after clicking the Between effects button. The design for the factor effects can be specified in the same manner as described in the context of the General Linear Models. In that case, the categorical factor effects and the interactions are transformed into the coded vectors of a design matrix, and the analysis is performed on the vectors of the resulting design matrix.