User Guide

102
Chapter 11

Simple. Each category of the predictor variable except the reference category is
compared to the reference category.
 Difference. Each category of the predictor variable except the first category is
compared to the average effect of previous categories. Also known as reverse
Helmert contrasts.
 Helmert. Each category of the predictor variable except the last category is
compared to the average effect of subsequent categories.
 Repeated. Each category of the predictor variable except the first category is
compared to the category that precedes it.
 Polynomial. Orthogonal polynomial contrasts. Categories are assumed to be equally
spaced. Polynomial contrasts are available for numeric variables only.
 Deviation. Each category of the predictor variable except the reference category is
compared to the overall effect.
If you select
Deviation, Simple, or Indicator, select either First or Last as the reference
category. Note that the method is not actually changed until you click
Change.
String covariates must be categorical covariates. To remove a string variable from
the Categorical Covariates list, you must remove all terms containing the variable from
the Covariates list in the main dialog box.
Cox Regression Plots
Figure 11-3
Cox Regression Plots dialog box