lrs.multistate {RISCA}

Likelihood Ratio Statistic to Compare Embedded Multistate Models

Description

This function computes a Likelihood Ratio Statistic to compare two embedded multistate models.

Usage

lrs.multistate(model1, model0)

Arguments

model1

A list containing the results after using a function included in the present RISCA package.

model0

A list containing the results after using a function included in the present RISCA package. The function used to obtained the model0 have to be the same than the one used to obtain the model1. The model0 have to be embedded in the model1.

Value

statistic

The value of the statistic.

ddl

The degrees of freedom.

pvalue

The p-value.

Author(s)

Yohann Foucher <[e-mail]>

Florence Gillaizeau <[e-mail]>

Examples

data(dataDIVAT1)

# A subgroup analysis to reduce the time needed for this example

dataDIVAT1$id<-c(1:nrow(dataDIVAT1))
set.seed(2)
d3<-dataDIVAT1[dataDIVAT1$id %in% sample(dataDIVAT1$id, 250, replace = FALSE),]

# To illustrate the use of a 3-state model, individuals with trajectory 13 and 123 are 
# censored at the time of transition into state X=3

d3$trajectory[d3$trajectory==13]<-1
d3$trajectory[d3$trajectory==123]<-12
d3$trajectory[d3$trajectory==14]<-13
d3$trajectory[d3$trajectory==124]<-123

# 3-state parametric semi-Markov model : does 'z' influence both the
# transition 1->3 ? We only reduced the precision and the number of iteration
# to save time in this example, prefere the default values.

m1 <- semi.markov.3states(times1=d3$time1, times2=d3$time2,
  sequences=d3$trajectory, dist=c("E","E","E"),
  ini.dist.12=c(9.93), ini.dist.13=c(11.54), ini.dist.23=c(10.21),
  cov.12=d3$z, init.cov.12=c(-0.13), names.12=c("beta12_z"),
  cov.13=d3$z, init.cov.13=c(1.61),  names.13=c("beta13_z"),
  conf.int=TRUE, silent=FALSE, precision=0.001)
  
m1

m0 <- semi.markov.3states(times1=d3$time1, times2=d3$time2,
  sequences=d3$trajectory, dist=c("E","E","E"),
  ini.dist.12=c(9.93), ini.dist.13=c(11.54), ini.dist.23=c(10.21),
  cov.12=d3$z, init.cov.12=c(-0.13), names.12=c("beta12_z"),
  conf.int=TRUE, silent=FALSE, precision=0.001)

m0

lrs.multistate(model1=m1, model0=m0)