% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/S3vcov.R
\name{vcov}
\alias{vcov}
\alias{vcov.MIRT}
\alias{vcov.MGPCM}
\alias{vcov.MGGUM}
\alias{vcov.FCMIRT}
\alias{vcov.FCDCM}
\alias{vcov.FCGDINA}
\alias{vcov.FCGGUM}
\alias{vcov.TIRT}
\title{S3 Methods: vcov}
\usage{
\method{vcov}{MIRT}(object, ...)

\method{vcov}{MGPCM}(object, ...)

\method{vcov}{MGGUM}(object, ...)

\method{vcov}{FCMIRT}(object, ...)

\method{vcov}{FCDCM}(object, ...)

\method{vcov}{FCGDINA}(object, ...)

\method{vcov}{FCGGUM}(object, ...)

\method{vcov}{TIRT}(object, ...)
}
\arguments{
\item{object}{A fitted model object of class \code{"MIRT"},
\code{"MGPCM"}, \code{"MGGUM"}, \code{"FCMIRT"}, \code{"FCDCM"},
\code{"FCGDINA"}, \code{"FCGGUM"}, or \code{"TIRT"}.}

\item{...}{Additional arguments (currently ignored).}
}
\value{
A square numeric matrix. Rows and columns correspond to the
free model parameters in the package's canonical parameter map.
}
\description{
Returns the variance--covariance matrix of the estimated model
parameters from a fitted \pkg{ForceChoice} model object. The package stores
marginal standard errors rather than a joint covariance estimate, so the
returned matrix is \eqn{\mathrm{diag}(\mathrm{SE}^2)} for every backend.
}
\details{
Standard errors reflect the active estimation backend. Off-diagonal
covariances are not retained in fitted objects and are therefore reported
as zero. Parameters whose standard errors were not estimated have
\code{NA} diagonal entries.
}
\section{Methods (by class)}{
\itemize{
\item \code{vcov(MIRT)}: Variance--covariance matrix of parameter estimates
for \code{MIRT} objects.

\item \code{vcov(MGPCM)}: Variance--covariance matrix for \code{MGPCM} objects.

\item \code{vcov(MGGUM)}: Variance--covariance matrix for \code{MGGUM} objects.

\item \code{vcov(FCMIRT)}: Variance--covariance matrix for \code{FCMIRT} objects.

\item \code{vcov(FCDCM)}: Variance--covariance matrix for \code{FCDCM} objects.

\item \code{vcov(FCGDINA)}: Variance--covariance matrix for \code{FCGDINA} objects.

\item \code{vcov(FCGGUM)}: Variance--covariance matrix for \code{FCGGUM} objects.

\item \code{vcov(TIRT)}: Variance--covariance matrix for \code{TIRT} objects.

}}
