[R] Problem comparing hazard ratios
Frank E Harrell Jr
f.harrell at Vanderbilt.Edu
Tue Mar 30 21:56:34 CEST 2010
Michal Figurski wrote:
> Dear R-Helpers,
> I am a novice in survival analysis. I have the following code:
> for (i in 3:12) print(coxph(Surv(time, status)~a[,i], data=a))
> I used it to fit the Cox Proportional Hazard models separately for every
> available parameter (columns 3:12) in my data set - with intention to
> compare the Hazard Ratios.
> However, some of my variables are in range 0.1 to 1.6, others in range
> 5000 to 9000. How do I compare HRs between such variables?
> I have rescaled all the variables to be in 0 to 1 range - is this the
> proper way to go? Is there a way to somehow calculate the same HRs (as
> for rescaled parameters) from the HRs for original parameters?
> Many thanks in advance.
There are a lot of issues related to this that will require a good bit
of study, both in survival analysis and in regression. I would start
with bootstrapping the ranks of the likelihood ratio chi-square
statistics of the competing biomarkers.
Frank E Harrell Jr Professor and Chairman School of Medicine
Department of Biostatistics Vanderbilt University
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