[R] Hazard ratio

[R Help]

Yes, in this case it's comparing to the value '1'.  In general with
factors it's comparing to whatever level is missing.

Sam

On Thu, Dec 10, 2009 at 10:40 AM, Ashta <sewashm at gmail.com> wrote:
> David,
>
> Thank you very much for your response.
>
> I fitted the model as  factor instead of numeric.
>
> coxfit1 <- coxph(Surv(sdat$time, sdat$cens)~factor(y1)+factor(x2)
>                               coef         exp(coef)  se(coef)      z
>       Pr(>|z|)
> factor(y1)2  0.036161  1.036822  0.083921  0.431   0.6665
> factor(y1)3  -0.510124  0.600421  0.088901 -5.738  9.57e-09 ***
> factor(x2)2  -0.510124  0.600421  0.088901 -5.738  9.57e-09 ***
>
>
>
> What are those values?   Is it comparing in reference to the first
> class of each covariate?
>
> Thanks again.
>
>
>
>
>
>
> On Thu, Dec 10, 2009 at 8:33 AM, Ashta <sewashm at gmail.com> wrote:
>> Hi all,
>>
>> I want to calculate  hazard  ratio within each covariate
>>
>>
>> Example, one covariate has 3 classes (1,2 and 3) and x2 has 2 classes
>>
>> I want to compare the relative risk ratio within each class of the covariate.
>>  How do I get this result ? .
>>
>>
>> The other question is that how do I interpret  the second column in
>> the second panel  (i.e., exp(-coef))
>>
>> I used the model
>> coxfit1 <- coxph(Surv(sdat$time, sdat$cens)~ y1+x2)
>>
>>           coef       exp(coef)  se(coef)       z          Pr(>|z|)
>> y1    -0.024084  0.976204  0.003077 -7.828 5.00e-15 ***
>> x2     0.036161  1.036822  0.083921  0.431   0.6665
>>
>>         exp(coef)  exp(-coef)   lower .95    upper .95
>>  y1      0.9762     1.0244       0.9703         0.9821
>> x2      1.0368      0.9645       0.8796         1.2222
>>
>>
>> Thanks in advance
>>
>
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