TAM (version 1.995-0)

IRT.itemfit.tam: RMSEA Item Fit Statistics for TAM Objects

Description

Computes the RMSEA item fit statistic for fitted objects in the TAM package, see CDM::IRT.itemfit and CDM::itemfit.rmsea.

Usage

"IRT.itemfit"(object, method="rmsea", ...)
"IRT.itemfit"(object, method="rmsea", ...)
"IRT.itemfit"(object, method="rmsea", ...)
"IRT.itemfit"(object, method="rmsea", ...)

Arguments

object

Object of class tam.mml, tam.mml.2pl, tam.mml.mfr or tam.mml.3pl.

method

Requested method for item fit calculation. Currently, only the RMSEA fit statistic (CDM::itemfit.rmsea) can be used.

...

Further arguments to be passed.

See Also

CDM::IRT.itemfit, CDM::itemfit.rmsea

Examples

## Not run: 
# #############################################################################
# # EXAMPLE 1: RMSEA item fit statistic data.read
# #############################################################################
# 
# library(sirt)
# data(data.read,package="sirt")
# dat <- data.read
# 
# #*** fit 1PL model
# mod1 <- tam.mml( dat )
# summary(mod1)
# 
# #*** fit 2PL model
# mod2 <- tam.mml.2pl( dat )
# summary(mod2)
# 
# #*** assess RMSEA item fit
# fmod1 <- IRT.itemfit(mod1)
# fmod2 <- IRT.itemfit(mod2)
# # summary of fit statistics
# summary( fmod1$rmsea )
# summary( fmod2$rmsea )
# 
# #############################################################################
# # SIMULATED EXAMPLE 2: Simulated 2PL data and fit of 1PL model
# #############################################################################
# 
# set.seed(987)
# N <- 1000    # 1000 persons
# I <- 10      # 10 items
# # define item difficulties and item slopes
# b <- seq(-2,2,len=I)
# a <- rep(1,I)
# a[c(3,8)] <- c( 1.7 , .4 )
# # simulate 2PL data
# dat <- sirt::sim.raschtype( theta=rnorm(N) , b = b , fixed.a = a)
# 
# # fit 1PL model
# mod <- tam.mml( dat )
# 
# # RMSEA item fit
# fmod <- IRT.itemfit(mod)
# round( fmod$rmsea , 3 )
# ## End(Not run)