IRT.likelihood function

S3 Methods for Extracting of the Individual Likelihood and the Individual Posterior

Functions for extracting the individual likelihood and individual posterior distribution.

IRT.likelihood(object, ...)

IRT.posterior(object, ...)

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

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

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

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

## S3 method for class 'reglca'
IRT.likelihood(object, ...)
## S3 method for class 'reglca'
IRT.posterior(object, ...)

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

Arguments

• object: Object of classes din, gdina, mcdina, gdm, slca, reglca.
• ...: More arguments to be passed.

Returns

For both functions IRT.likelihood and IRT.posterior, it is a matrix with attributes - theta: Uni- or multidimensional skill space (theta grid in item response models).

• prob.theta: Probability distribution of theta

• skillspace: Design matrix and estimated parameters for skill space distribution (only for IRT.posterior.slca)

• G: Number of groups

See Also

GDINA::indlogLik, GDINA::indlogPost

Examples

#############################################################################
# EXAMPLE 1: Extracting likelihood and posterior from a DINA model
#############################################################################

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

#*** estimate model
mod1 <- CDM::din( sim.dina, q.matrix=sim.qmatrix, rule="DINA")
#*** extract likelihood
likemod1 <- CDM::IRT.likelihood(mod1)
str(likemod1)
# extract theta
attr(likemod1, "theta" )
#*** extract posterior
pomod1 <- CDM::IRT.posterior( mod1 )
str(pomod1)