vcov: S3 Methods: vcov

In ForceChoice: Forced-Choice Modeling Based on Item Response Theory and Cognitive Diagnostic Models

S3 Methods: vcov

Description

Returns the variance–covariance matrix of the estimated model parameters from a fitted ForceChoice model object. The package stores marginal standard errors rather than a joint covariance estimate, so the returned matrix is \mathrm{diag}(\mathrm{SE}^2) for every backend.

Usage

## S3 method for class 'MIRT'
vcov(object, ...)

## S3 method for class 'MGPCM'
vcov(object, ...)

## S3 method for class 'MGGUM'
vcov(object, ...)

## S3 method for class 'FCMIRT'
vcov(object, ...)

## S3 method for class 'FCDCM'
vcov(object, ...)

## S3 method for class 'FCGDINA'
vcov(object, ...)

## S3 method for class 'FCGGUM'
vcov(object, ...)

## S3 method for class 'TIRT'
vcov(object, ...)

Arguments

object	A fitted model object of class "MIRT", "MGPCM", "MGGUM", "FCMIRT", "FCDCM", "FCGDINA", "FCGGUM", or "TIRT".
...	Additional arguments (currently ignored).

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 NA diagonal entries.

Value

A square numeric matrix. Rows and columns correspond to the free model parameters in the package's canonical parameter map.

Methods (by class)

• vcov(MIRT): Variance–covariance matrix of parameter estimates for MIRT objects.

• vcov(MGPCM): Variance–covariance matrix for MGPCM objects.

• vcov(MGGUM): Variance–covariance matrix for MGGUM objects.

• vcov(FCMIRT): Variance–covariance matrix for FCMIRT objects.

• vcov(FCDCM): Variance–covariance matrix for FCDCM objects.

• vcov(FCGDINA): Variance–covariance matrix for FCGDINA objects.

• vcov(FCGGUM): Variance–covariance matrix for FCGGUM objects.

• vcov(TIRT): Variance–covariance matrix for TIRT objects.

ForceChoice documentation built on Sept. 13, 2026, 1:06 a.m.