[R] p-value=0 running coxph

[C.H.]

Because your test statistics (z=-9.16) is too small. (well, z> 1.96 or
Z < -1.96 is p=0.05)
If you really want the exact p, you can try
pnorm(-9.16)

if I were you I will quote p<0.001 as well as the test statistics. (if
you are going to submit it to medical journals)

C


On Thu, Oct 30, 2008 at 10:36 PM, GSt <gisela.sturm at i-med.ac.at> wrote:
>
> Dear all,
>
> I have a question concerning the p-value. When running coxph I get a p-value
> = 0. :confused:
> 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:
> ----------------------------------------------------------------------------------------------------
> Call:
> coxph(formula = Surv(start, stop, status) ~ Albumin_gproL, data = dial,
> na.action = na.omit, method = "breslow")
>
> n=22449 (31 observations deleted due to missingness)
>                       coef   exp(coef)   se(coef)         z    p
> Albumin_gproL -0.157         0.855     0.0172   -9.16    0
>
>                       exp(coef)    exp(-coef)    lower .95    upper .95
> Albumin_gproL         0.855             1.17         0.826         0.884
>
> Rsquare= 0.003   (max possible= 0.033 )
> Likelihood ratio test = 73.6  on 1 df,   p=0
> Wald test               = 83.8  on 1 df,   p=0
> Score (logrank) test = 86.1  on 1 df,   p=0
>
>> cox.zph(cox_1111)
>                          rho    chisq          p
> Albumin_gproL -0.0509    0.197    0.657
> ----------------------------------------------------------------------------------------------------
>
> Thank you in advance...
> GSt
> --
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>
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-- 
CH Chan
Research Assistant - KWH
http://www.macgrass.com