Displaying 3 results from an estimated 3 matches for "recidivismv".
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recidivism
2009 Mar 14
1
obtaining the values for the hazard function in a cox regression
...ed
me to obtain the hazard function values. I am wanting to confirm
whether basehaz is the correct command to obtain such values, to
better understand what is occurring in the log plots.
Below is the code that I have been using. Any assistance is appreciated,
regards
Bob
library(survival)
recidivismv <- read.csv("g://Chapsurv_v.csv",header=T)
cox.V <- coxph(Surv(intDaysUntilFVPO, Event_v) ~ intAgeAtMHCIndex +
PRE + group + MHC + strGender, data = recidivismv)
summary (cox.V)
# produces a log-log plot
mvfit <- survfit (Surv(recidivismv$intDaysUntilFVPO,
recidivismv$Event_...
2009 Mar 28
1
stratified variables in a cox regression
....g a separate
analysis for male and female if a gender variable were stratified). I
have not seen this approach used in R examples I have seen.
Below is my current code - is there a method to test whether the
stratified variables should be included in the final model at all?
library(survival)
recidivismv <- read.csv("g://Chapsurv_v.csv",header=T)
cox.V2 <- coxph(Surv(intDaysUntilFVPO, Event_v) ~ intAgeAtMHCIndex +
PRE + group + strata (MHC, strGender), data = recidivismv)
regards
Bob
2009 Mar 16
0
hazard function in a Cox model
...btain such values, to
better understand what is occurring in the log plots.
--- end inclusion ----
The best tool for understanding what is happening is cox.zph.
cox.V <- coxph(Surv(intDaysUntilFVPO, Event_v) ~ intAgeAtMHCIndex +
PRE + group + MHC + strGender, data = recidivismv)
zpfit <- cox.zph(cox.V, transform='identity')
plot( zpfitp[1]) #plot for the first variable
plot( zpfitp[2]) #plot for the second
You will get a plot of beta(t) versus time, a horizontal line corresponds to a
constant hazard ratio. The Cox model coefficient is an "av...