DATA MINING
Desktop Survival Guide by Graham Williams |
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More Input Variables |
> l.coxph <- coxph(Surv(time, status) ~ age + ph.ecog, data=lung, method="breslow") > summary(l.coxph) |
Call: coxph(formula = Surv(time, status) ~ age + ph.ecog, data = lung, method = "breslow") n=227 (1 observation deleted due to missingness) coef exp(coef) se(coef) z Pr(>|z|) age 0.011269 1.011333 0.009319 1.209 0.226544 ph.ecog 0.442693 1.556894 0.115819 3.822 0.000132 *** --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 exp(coef) exp(-coef) lower .95 upper .95 age 1.011 0.9888 0.993 1.030 ph.ecog 1.557 0.6423 1.241 1.954 Rsquare= 0.08 (max possible= 0.999 ) Likelihood ratio test= 18.99 on 2 df, p=0.00007506 Wald test = 19.19 on 2 df, p=0.00006796 Score (logrank) test = 19.49 on 2 df, p=0.00005873 |
Predict male survival from age and medical scores.
> l.coxph <- coxph(l.Surv ~ age + ph.ecog + ph.karno + pat.karno, data=lung, subset=sex==1) |
Display results:
> summary(l.coxph) |
Call: coxph(formula = l.Surv ~ age + ph.ecog + ph.karno + pat.karno, data = lung, subset = sex == 1) n=134 (4 observations deleted due to missingness) coef exp(coef) se(coef) z Pr(>|z|) age 0.022465 1.022719 0.012216 1.839 0.06593 . ph.ecog 0.665452 1.945370 0.225712 2.948 0.00320 ** ph.karno 0.025553 1.025883 0.011778 2.170 0.03004 * pat.karno -0.011059 0.989002 0.008892 -1.244 0.21361 --- Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 exp(coef) exp(-coef) lower .95 upper .95 age 1.023 0.9778 0.9985 1.048 ph.ecog 1.945 0.5140 1.2499 3.028 ph.karno 1.026 0.9748 1.0025 1.050 pat.karno 0.989 1.0111 0.9719 1.006 Rsquare= 0.125 (max possible= 0.998 ) Likelihood ratio test= 17.87 on 4 df, p=0.001311 Wald test = 18.3 on 4 df, p=0.001076 Score (logrank) test = 18.6 on 4 df, p=0.000942 |
Evaluate the proportional hazards assumption:
> cox.zph(l.coxph) |
rho chisq p age 0.00534 0.00363 0.952 ph.ecog 0.02851 0.09155 0.762 ph.karno 0.16922 2.43462 0.119 pat.karno 0.02988 0.12793 0.721 GLOBAL NA 5.62951 0.229 |
Now predict:
> head(lung$time) |
[1] 306 455 1010 210 883 1022 |
> head(predict(l.coxph, lung)) |
[,1] 1 0.2448093 2 -0.4448432 3 -0.7144239 4 0.3052630 5 -0.3690295 6 -0.5561473 |