The Define part of the program is used to set up a CHAID Definition (.chd) file with the File → New command, or alter the specifications of an existing .chd file with File → Open. The typical setup includes the selection of the dependent variable, the predictor variables, the combine-type of the predictors, and various options for growing the tree (stopping rule, significance levels, etc.). Define may also be used to enter or modify scores for the categories of the dependent variable when the ordinal algorithm is specified. The model specifications, which are saved with a .chd extension, can be inspected with a text editor (Notepad, for example).
The Explore part of the program allows you to grow or alter a SI-CHAID Tree, automatically or interactively, using the settings given in a previously saved (.chd) file. It can also be used to produce crosstabulations, gains charts, and if-then-else source code statements that can assist in scoring your data file.