nathalcs at student.matnat.uio.no
2010-Mar-19 15:07 UTC
[R] Different results from survreg with version 2.6.1 and 2.10.1
---------------------------- Original Message ---------------------------- Subject: Different results from survreg with version 2.6.1 and 2.10.1 From: nathalcs at ulrik.uio.no Date: Fri, March 19, 2010 16:00 To: r-help at r-project.org -------------------------------------------------------------------------- Dear all I'm using survreg command in package survival. sur2=survreg(Surv((levetid-364),status==2)~vekt.ind,control=list(maxiter=50),data=ord.mfr) When using R version 2.6.1 (2007-11-26) i386-pc-mingw32 I get this result summary(sur2) Call: survreg(formula = Surv((levetid - 364), status == 2) ~ malder + faar + gest + vekt.ind, data = ord.mfr, control = list(maxiter = 50)) Value Std. Error z p (Intercept) 1.49e+01 1.73105 8.5993 8.02e-18 malder 9.22e-02 0.01955 4.7178 2.38e-06 faar 2.78e-02 0.01308 2.1272 3.34e-02 gest 3.79e-04 0.00528 0.0718 9.43e-01 vekt.ind 8.46e-01 0.19575 4.3234 1.54e-05 Log(scale) 6.83e-01 0.03651 18.7086 4.22e-78 Scale= 1.98 Weibull distribution Loglik(model)= -11108.6 Loglik(intercept only)= -11136.6 Chisq= 55.87 on 4 degrees of freedom, p= 2.1e-11 Number of Newton-Raphson Iterations: 13 n= 254572 while when using R version 2.10.1 (2009-12-14) i386-pc-mingw32 this is what I get ummary(sur2) Call: survreg(formula = Surv((levetid - 364), status == 2) ~ malder + faar + gest + vekt.ind, data = ord.mfr, control = list(maxiter = 50)) Value Std. Error z p (Intercept) -7.95477 2.83e-34 -2.81e+34 0 malder 0.01635 2.61e-36 6.25e+33 0 faar 0.29213 2.60e-36 1.12e+35 0 gest -0.00275 7.54e-37 -3.64e+33 0 vekt.ind 0.28575 2.96e-35 9.64e+33 0 Log(scale) -95.89809 5.88e-36 -1.63e+37 0 Scale= 2.25e-42 Weibull distribution Loglik(model)= -82219.2 Loglik(intercept only)= -11136.6 Chisq= -142165.2 on 4 degrees of freedom, p= 1 Number of Newton-Raphson Iterations: 2 n= 254572 which is quite different results, with the result with version 2.6.1 being the most reasonable. But if I for instance do a cox-regression on on the same data with the same covariate with the two different versions I do get the same result, which is how it should be R version 2.6.1 (2007-11-26): print(coxfit2) Call: coxph(formula = Surv(levetid, status == 2) ~ malder + faar + gest + vekt.ind, data = ord.mfr) coef exp(coef) se(coef) z p malder -0.046320 0.955 0.00972 -4.767 1.9e-06 faar -0.040658 0.960 0.00639 -6.367 1.9e-10 gest -0.000211 1.000 0.00267 -0.079 9.4e-01 vekt.ind -0.427916 0.652 0.09765 -4.382 1.2e-05 Likelihood ratio test=102 on 4 df, p=0 n= 254572 R version 2.10.1 (2009-12-14): print(coxfit2) Call: coxph(formula = Surv(levetid, status == 2) ~ malder + faar + gest + vekt.ind, data = ord.mfr) coef exp(coef) se(coef) z p malder -0.046320 0.955 0.00972 -4.767 1.9e-06 faar -0.040658 0.960 0.00639 -6.367 1.9e-10 gest -0.000211 1.000 0.00267 -0.079 9.4e-01 vekt.ind -0.427916 0.652 0.09765 -4.382 1.2e-05 Likelihood ratio test=102 on 4 df, p=0 n= 254572 My question is why do this happen with survreg? Best regards Nathalie St?er