[R] Cox Proportional Hazards

Nanthinee Jeevanandam nanthineej at gmail.com
Tue Aug 21 12:40:01 CEST 2012


 I have run this model for my data set on insect survival time for
different temperature treatments in R. I understand the Wald statistic
reports on whether the variable
makes a difference to the model but there is also a p-value so i am
not sure whther to report the Wald statistic. I have pasted a copy of
my result below. Humidity is categorical (a & b) while temperature is
continuous.

coxph(formula = Surv(time, death) ~ Humidity + temp)
n= 1504, number of events= 1504

               coef   exp(coef) se(coef)          z    Pr(>|z|)
Hum.b -0.03023   0.97022  0.05695   -0.531    0.595
temp   1.19094   3.29017  0.03360   35.444   <2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

          exp(coef) exp(-coef) lower .95 upper .95
Humb    0.9702     1.0307    0.8678     1.085
temp      3.2902     0.3039    3.0805     3.514

Concordance= 0.918  (se = 0.013 )
Rsquare= 0.742   (max possible= 1 )
Likelihood ratio test= 2036  on 2 df,   p=0
Wald test            = 1281  on 2 df,   p=0
Score (logrank) test = 1948  on 2 df,   p=0


How do I interpret the Wald test in this case?  Really appreciate the help.

nj



More information about the R-help mailing list