# p-value=0 running log-rank test

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## p-value=0 running log-rank test

 Dear all, I have a question concerning the p-value. When running log-rank test I get a p-value = 0. What is it mean? Can this be true? Why aren´t there decimal points? Is there a way to find out the exact p-value? Here is the output: > survdiff(Surv(tempo2,status)~tphist, data=base,rho=0) Call: survdiff(formula = Surv(tempo2, status) ~ tphist, data = base,     rho = 0)            N Observed Expected (O-E)^2/E (O-E)^2/V tphist=1 513       19   40.879    11.710  9.00e+01 tphist=2  49        4    3.892     0.003  3.27e-03 tphist=3  23        9    1.686    31.717  3.29e+01 tphist=4  18       15    0.543   385.172  3.91e+02  Chisq= 430  on 3 degrees of freedom, p= 0 Thank you in advance. Anne.         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: [FORGED] p-value=0 running log-rank test

 This is not an R question. Your question indicates that you really need to learn some statistics. To answer the very last part:  > pchisq(430,3,lower=FALSE) [1] 7.020486e-93 And if that is not 0 to all intents and purposes, then God help us all. cheers, Rolf Turner On 19/05/17 12:48, Anne Karin da Mota Borges wrote: > Dear all, > > I have a question concerning the p-value. When running log-rank test I get > a p-value = 0. > What is it mean? Can this be true? Why aren´t there decimal points? Is > there a way to find out the exact p-value? > > Here is the output: > >> survdiff(Surv(tempo2,status)~tphist, data=base,rho=0) > Call: > survdiff(formula = Surv(tempo2, status) ~ tphist, data = base, >     rho = 0) > >            N Observed Expected (O-E)^2/E (O-E)^2/V > tphist=1 513       19   40.879    11.710  9.00e+01 > tphist=2  49        4    3.892     0.003  3.27e-03 > tphist=3  23        9    1.686    31.717  3.29e+01 > tphist=4  18       15    0.543   385.172  3.91e+02 > >  Chisq= 430  on 3 degrees of freedom, p= 0 > > Thank you in advance. ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.