Hi, sorry about that; here is the full output - data set, structure, model and result.
Cheers Jacob > seedlings cohort death gapsize status 1 September 7 0.5889 1 2 September 3 0.6869 1 3 September 12 0.1397 1 4 September 1 0.1921 1 5 September 4 0.2798 1 6 September 2 0.2607 1 7 September 6 0.9467 1 8 September 6 0.6375 1 9 September 8 0.1527 1 10 September 3 0.8237 1 11 September 1 0.5979 1 12 September 1 0.2914 1 13 September 3 0.5053 1 14 September 5 0.4714 1 15 September 2 0.6041 1 16 September 8 0.8812 1 17 September 4 0.8416 1 18 September 1 0.0577 1 19 September 2 0.9034 1 20 September 2 0.4348 1 21 September 7 0.9878 1 22 September 11 0.1486 1 23 September 14 0.5003 1 24 September 1 0.8507 1 25 September 10 0.8187 1 26 September 14 0.0291 1 27 September 1 0.3785 1 28 September 4 0.8384 1 29 September 2 0.8351 1 30 September 2 0.9674 1 31 October 1 0.6943 1 32 October 1 0.2591 1 33 October 2 0.7397 1 34 October 2 0.4663 1 35 October 14 0.9115 1 36 October 5 0.1750 1 37 October 1 0.5628 1 38 October 8 0.2681 1 39 October 5 0.6967 1 40 October 2 0.7020 1 41 October 4 0.7971 1 42 October 3 0.4047 1 43 October 5 0.0498 1 44 October 10 0.0364 1 45 October 9 0.4080 1 46 October 1 0.6226 1 47 October 11 0.3002 1 48 October 3 0.8111 1 49 October 21 0.4894 1 50 October 1 0.0375 1 51 October 4 0.2560 1 52 October 9 0.2168 1 53 October 8 0.7437 1 54 October 1 0.9082 1 55 October 3 0.9496 1 56 October 9 0.1040 1 57 October 9 0.8691 1 58 October 16 0.9502 1 59 October 6 0.0790 1 60 October 1 0.5658 1 > str(seedlings) 'data.frame': 60 obs. of 4 variables: $ cohort : Factor w/ 2 levels "October","September": 2 2 2 2 2 2 2 2 2 2 ... $ death : int 7 3 12 1 4 2 6 6 8 3 ... $ gapsize: num 0.589 0.687 0.14 0.192 0.28 ... $ status : num 1 1 1 1 1 1 1 1 1 1 ... > model1 <- coxph(Surv(death,status)~strata(cohort)*gapsize,data=seedlings) > 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 28 jun 2011 kl. 15.48 skrev Robert A LaBudde: > Did you create the 'status' variable the way indicated on p. 797? > > Frequently with Surv() it pays to use syntax such as Surv(death, status==1) > to make a clear logical statement of what is an event (status==1) vs. > censored. > > PS. Next time include head(seedlings) and str(seedlings) to make clear what > you are using as data. > > > At 06:51 AM 6/28/2011, Jacob Brogren wrote: >> 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. > > ================================================================ > Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: r...@lcfltd.com > Least Cost Formulations, Ltd. URL: http://lcfltd.com/ > 824 Timberlake Drive Tel: 757-467-0954 > Virginia Beach, VA 23464-3239 Fax: 757-467-2947 > > "Vere scire est per causas scire" > ================================================================ > ______________________________________________ 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.