Dear list,



I ran a conditional frailty model with an interaction term (see below). To
interpret the interaction term, I would like to produce plots that reflect
how does a moderator variable (“ecogr”) shape the effect of the other
interacted variable (“elderly”).



condfrailty.gamma.em <-coxph(Surv(evst,evdur,pere) ~ ecogr+ elderly+
elderly_ecogr+strata(strata)+

frailty(country,distribution="gamma",method="em"),
method=c("efron"),data=ret)

summary(condfrailty.gamma.em)



plot(condfrailty.gamma.em,fun=”cumhaz”, lty=1, ylab=””,xlab=””,ylim=c(0,4))



However, the plot command after this function only produces the hazard rate
for each event strata. Is there a syntax to produce a single hazard rate for
all the strata?



Moreover, is it possible to obtain hazard rates for specific ranges in the
independent variables? I would like to produce two plots. Plot #1 would
provide the rates when “ecogr” is below its mean and “elderly” is,
respectively, one standard deviation above and one below its mean.Plot #2
would provide the rates when “ecogr” is above its mean and “elderly” is,
respectively, one standard deviation above and below its mean.



Thanks,



Juan

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