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Chapter 12
Predictors
Figure 12-3
Cox Regression dialog box, Predictors tab
The Predictors t ab allows you to specify the factors and covariates used to b uild model effects.
Factors
.
Factors are categorical predictors; they can be numeric or string.
Covariates. Covariates are scale predictors; they must be numeric.
Time-Dependent Predictors. There are certain situations in which the proportional hazards
assump
tion does not hold. That is, hazard ratios change across time; the values of one (or more)
of your predictors are different at different time points. In such cases, you need to specify
time-dependent predictors. For more information, see the topic Define Time-Dependent Predictor
on p. 79. T
ime-dependent predictors can be selected as factors or covariates.