Hi Mukesh,
Since R does not have any function to calculate concordance,we need to create one:
concordance<-function(model){
# Get all actual observations and their fitted values into a frame
fitted<-data.frame(cbind(model$y,model$fitted.values))
colnames(fitted)<-c('respvar','score')
# Subset only ones
ones<-fitted[fitted[,1]==1,]
# Subset only zeros
zeros<-fitted[fitted[,1]==0,]
# Initialise all the values
pairs_tested<-0
conc<-0
disc<-0
ties<-0
# Get the values in a for-loop
for(i in 1:nrow(ones))
{
for(j in 1:nrow(zeros))
{
pairs_tested<-pairs_tested+1
if(ones[i,2]>zeros[j,2]) {conc<-conc+1}
else if(ones[i,2]==zeros[j,2]){ties<-ties+1}
else {disc<-disc+1}
}
}
# Calculate concordance, discordance and ties
concordance<-conc/pairs_tested
discordance<-disc/pairs_tested
ties_perc<-ties/pairs_tested
return(list("Concordance"=concordance,
"Discordance"=discordance,
"Tied"=ties_perc,
"Pairs"=pairs_tested))
}
Hope this helps!!