Workspace Node: Advanced Regression CHAID - Specifications - Stopping Tab

In the Advanced Regression CHAID workspace node dialog box, under the Specifications heading, select the Stopping tab to access options to keep a check on the size of the tree. The size of the tree is an important issue in computing classification and regression trees; you don't want the tree to grow to an undesirable size, which can make the interpretation of results difficult.

Element Name Description
Stopping parameters These parameters determine when the tree building process will terminate.
Minimum n (%) of cases Enter a value for the Minimum n of cases. If the number of observations within the node is less than this value, the node will not be considered for splitting.
Minimum n in child nodes Use this option to control the smallest permissible number in a child node, for a split to be applied. While the Minimum n of cases parameter determines whether an additional split is considered at any particular node, the Minimum n in child node parameter determines whether a split will be applied, depending on whether any of the resultant child nodes will be smaller (have fewer cases) than n as specified via this option.
Maximum n of levels Use this option to specify the maximum number (n) of levels in the tree.
Maximum n of nodes Enter a value to stop splitting on the basis of the number of nodes in the classification tree. Each time a split occurs, the total number of nodes in the tree is examined and the splitting process is stopped if this number exceeds the number specified as Maximum n of nodes.
Prob. for splitting. As described in Basic Tree-Building Algorithm: CHAID and Exhaustive CHAID, the tree building (split selection) will continue until no further splits can be found that are statistically significant (see also Bonferroni adjustment) at the level specified here as the Probability for splitting.
Prob. for merging. As described in Basic Tree-Building Algorithm: CHAID and Exhaustive CHAID, the tree building computations involve the merging of predictor categories (artificially created for continuous predictors) that are not statistically significant with respect to the dependent variable (Chi-square tests are computed for categorical dependent variables, and F tests are computed for continuous dependent variables). If no further merging can be performed, giving the Probability for merging defined here, and if no further splits can be performed consistent with the other stopping criteria specified on this tab, the tree-building (split selection) computations will terminate.

Options / C / W. See Common Options.

OK Click this button to accept all the specifications made in the dialog box and to close it. The analysis results are placed in the Reporting Documents workspace node after running (updating) the project.