On Jan 4, 2014, at 8:37 PM, zhu yao wrote: > I have use the plot(summary(cph-fit)) to plot the hazard ratio plot. > *Can I change the reference level in the plot, for example, use [1999, > 2002) as the reference level?*
I do not think we have enough information to be sure what you mean, but I would remind you that Cox models are always estimations of the relative risk for differences in covariates. If the era for which 1999-2002 is one instance as a covariate (rather than as the time variable), then you could certainly construct differences from that era. -- David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
