Hi, I ran the example on pp. 799-800 from Machael Crawley's "The R Book" using package survival v. 2.36-5, R 2.13.0 and RStudio 0.94.83. The model is a Cox's Proportional Hazards model. The result was quite different compared to the R Book. I have compared my code to the code in the book but can not find any differences in the function call. My results are attached as well as a link to the results presented in the book (link to Google Books).
When running the examples on pp. 797-799 I can't detect any differences in results so I don't think there are errors in the data set or in the creation of the status variable. --------------------------------- Original from the R Book: http://books.google.com/books?id=8D4HVx0apZQC&lpg=PA799&ots=rQgd_8ofeS&dq=r%20coxph%20crawley&pg=PA799#v=onepage&q&f=false --------------------------------- My result: > summary(model1) Call: coxph(formula = Surv(death, status) ~ strata(cohort) * gapsize, data = seedlings) n= 60, number of events= 60 coef exp(coef) se(coef) z Pr(>|z|) gapsize -0.001893 0.998109 0.593372 -0.003 0.997 gapsize:strata(cohort)cohort=September 0.717407 2.049112 0.860807 0.833 0.405 exp(coef) exp(-coef) lower .95 upper .95 gapsize 0.9981 1.002 0.3120 3.193 gapsize:strata(cohort)cohort=September 2.0491 0.488 0.3792 11.074 Rsquare= 0.022 (max possible= 0.993 ) Likelihood ratio test= 1.35 on 2 df, p=0.5097 Wald test = 1.32 on 2 df, p=0.5178 Score (logrank) test = 1.33 on 2 df, p=0.514 Anyone have an idea why this is occurring? Kind Regards Jacob ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
