The SAS System 09:34 Monday, April 1, 2002 74
The PHREG Procedure
Data Set: WORK.EX17_5
Dependent Variable: T
Censoring Variable: Y
Censoring Value(s): 1
Ties Handling: BRESLOW
Summary of the Number of
Event and Censored Values
Percent
Total Event Censored Censored
63 26 37 58.73
Step 1: Variable X4 is entered. The model contains the following explanatory variables.
X4
Testing Global Null Hypothesis: BETA=0
Without With
Criterion Covariates Covariates Model Chi-Square
-2 LOG L 201.994 187.690 14.304 with 1 DF (p=0.0002)
Score . . 13.040 with 1 DF (p=0.0003)
Wald . . 10.265 with 1 DF (p=0.0014)
Step 2: Variable X5 is entered. The model contains the following explanatory variables.
X4 X5
Testing Global Null Hypothesis: BETA=0
Without With
Criterion Covariates Covariates Model Chi-Square
-2 LOG L 201.994 182.777 19.217 with 2 DF (p=0.0001)
Score . . 17.594 with 2 DF (p=0.0002)
Wald . . 14.579 with 2 DF (p=0.0007)
NOTE: No (additional) variables met the 0.05 level for entry into the model.
The SAS System 09:34 Monday, April 1, 2002 75
The PHREG Procedure
Analysis of Maximum Likelihood Estimates
Parameter Standard Wald Pr > Risk
Variable DF Estimate Error Chi-Square Chi-Square Ratio
X4 1 1.761621 0.54791 10.33726 0.0013 5.822
X5 1 0.931330 0.44455 4.38899 0.0362 2.538
Summary of Stepwise Procedure
Variable Number Score Wald Pr >
Step Entered Removed In Chi-Square Chi-Square Chi-Square
1 X4 1 13.0399 . 0.0003
2 X5 2 4.7039 . 0.0301
