S3 Methods for Assessing Model Fit

This S3 method assesses global (absolute) model fit using the methods described in modelfit.cor.din.

IRT.modelfit(object, ...)

# S3 method for din
IRT.modelfit(object, ...)
# S3 method for gdina
IRT.modelfit(object, ...)

# S3 method for IRT.modelfit.din
summary(object, ...)
# S3 method for IRT.modelfit.gdina
summary(object, ...)

Arguments

object	Object of classes din or gdina.
...	More arguments to be passed.

Value

See output of modelfit.cor.din.

See also

For extracting the individual likelihood or posterior see IRT.likelihood or IRT.posterior.

The model fit of objects of class gdm can be obtained by using the TAM::tam.modelfit.IRT function in the TAM package.

Examples

if (FALSE) {
#############################################################################
# EXAMPLE 1: Absolute model fit
#############################################################################

data(sim.dina, package="CDM")
data(sim.qmatrix, package="CDM")

#*** Model 1: DINA model for DINA simulated data
mod1 <- CDM::din( sim.dina, q.matrix=sim.qmatrix, rule="DINA" )
fmod1 <- CDM::IRT.modelfit( mod1 )
summary(fmod1)
  ##  Test of Global Model Fit
  ##         type value     p
  ##  1   max(X2) 8.728 0.113
  ##  2 abs(fcor) 0.143 0.080
  ##
  ##  Fit Statistics
  ##                    est
  ##  MADcor          0.030
  ##  SRMSR           0.040
  ##  100*MADRESIDCOV 0.671
  ##  MADQ3           0.062
  ##  MADaQ3          0.059

#*** Model 2: GDINA model
mod2 <- CDM::gdina( sim.dina, q.matrix=sim.qmatrix, rule="GDINA" )
fmod2 <- CDM::IRT.modelfit( mod2 )
summary(fmod2)
  ##  Test of Global Model Fit
  ##         type value p
  ##  1   max(X2) 2.397 1
  ##  2 abs(fcor) 0.078 1
  ##
  ##  Fit Statistics
  ##                    est
  ##  MADcor          0.023
  ##  SRMSR           0.030
  ##  100*MADRESIDCOV 0.515
  ##  MADQ3           0.075
  ##  MADaQ3          0.071
}