frailtypack (version 2.2-13)

slope: Identify variable associated with the random slope

Description

This is a special function used in the context of survival additive models. It identifies the variable which is in interaction with the random slope ($v_i$). Generally, this variable is the treatment variable. Using interaction() in a formula implies that an additive frailty model is fitted.

Usage

slope(x)

Arguments

x

A factor, a character or a numerical variable

Value

• x
  The variable in interaction with the random slope

See Also

additivePenal, print.additivePenal, plot.additivePenal, summary.additivePenal

Examples

library(frailtypack)
data(dataAdditive)


# Additive with one covariate #

modAdd1cov<-additivePenal(Surv(t1,t2,event)~cluster(group)+var1+
slope(var1),data=dataAdditive,n.knots=8,kappa1=10000)


# Additive with two covariates #

set.seed(1234)
dataAdditive$var2<-rbinom(nrow(dataAdditive),1,0.5)

modAdd2cov<-additivePenal(Surv(t1,t2,event)~cluster(group)+var1+var2+
slope(var1),data=dataAdditive,n.knots=8,kappa1=10000)


# Additive with 2 covariates and stratification #

dataAdditive$var2<-rbinom(nrow(dataAdditive),1,0.5)

modAddstrat<-additivePenal(Surv(t1,t2,event)~cluster(group)+strata(var2)+var1+
slope(var1),data=dataAdditive,n.knots=8,kappa1=10000,kappa2=10000)