IRT.frequencies function

S3 Method for Computing Observed and Expected Frequencies of Univariate and Bivariate Marginals

This S3 method computes observed and expected frequencies for univariate and bivariate distributions.

IRT.frequencies(object, ...)

IRT_frequencies_default(data, post, probs, weights=NULL)

IRT_frequencies_wrapper(object, ...)

## S3 method for class 'din'
IRT.frequencies(object, ...)

## S3 method for class 'gdina'
IRT.frequencies(object, ...)

## S3 method for class 'mcdina'
IRT.frequencies(object, ...)

## S3 method for class 'gdm'
IRT.frequencies(object, ...)

## S3 method for class 'slca'
IRT.frequencies(object, ...)

Arguments

• object: Object of classes din, gdina, mcdina, gdm or slca.

• ...: More arguments to be passed.

• data: Item response data as extracted by IRT.data

• post: Individual posterior distribution as extracted by IRT.posterior

• probs: Individual posterior distribution as extracted by IRT.irfprob

• weights: Optional vector of weights as included as the attribute weights

  in IRT.data

Returns

List with following entries

• uni_obs: Univariate observed distribution

• uni_exp: Univariate expected distribution

• M_obs: Univariate observed means

• M_exp: Univariate expected means

• SD_obs: Univariate observed standard deviations

• SD_exp: Univariate expected standard deviations

• biv_obs: Bivariate observed frequencies

• biv_exp: Bivariate expected frequencies

• biv_N: Bivariate sample size

• cov_obs: Observed covariances

• cov_cor: Expected covariances

• cor_obs: Observed correlations

• cor_exp: Expected correlations

• chisq: Chi square statistic of local independence

Examples

## Not run:

#############################################################################
# EXAMPLE 1: Usage IRT.frequencies
#############################################################################

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

# estimate GDINA model
mod1 <- CDM::gdina( data=sim.dina,  q.matrix=sim.qmatrix)
summary(mod1)

# direct usage of IRT.frequencies
fres1 <- CDM::IRT.frequencies(mod1)

# use of the default function with input data
data <- CDM::IRT.data(object)
post <- CDM::IRT.posterior(object)
probs <- CDM::IRT.irfprob(object)
fres2 <- CDM::IRT_frequencies_default(data=data, post=post, probs=probs)
## End(Not run)