Max Number of Categories Allowed in a Predictor Use this option to specify the maximum number of categories allowed in a predictor variable. For predictors with more than this number of categories, the categories are grouped. To Specify the Maximum Number of Categories: Either type the maximum number of categories to allow per predictor into the text field, or move the slider to the right or to the left to specify a value. Tip : To change the scale of the slider, right-click on the slider and select Rescale Slider from the pop-up menu. Change the upper and/or lower boundaries in the window that appears, to rescale the slider and click OK .