install.packages("binomTools")
library("binomTools")
# The Rsq function computes several fit indices,
# including the coefficient of discrimination.
# For information on the other fit indices, see Tjur (2009).
# The plot shows the distribution of expected values when the outcome is observed
# and not observed.
# Ideally, the overlap between the two histograms should be small.
fit <- Rsq(object = logit.reg)
fit
# R-square measures and the coefficient of discrimination, 'D':
#
#    R2mod     R2res     R2cor     D
#    0.5205221 0.5024101 0.5025676 0.5114661
#
# Number of binomial observations:  70
# Number of binary observation:  70
# Average group size:  1 
plot(fit, which = "hist")