vcov.rasch {ltm}R Documentation

vcov method for rasch objects

Description

Extracts the asymptotic variance-covariance matrix of the MLEs from a rasch object.

Usage

## S3 method for class 'rasch':
vcov(object, robust = FALSE, ...)

Arguments

object an object inheriting from class rasch.
robust logical; if TRUE the sandwich estimator is used.
... additional arguments; currently none is used.

Value

a numeric matrix representing the estimated covariance matrix of the maximum likelihood estimates.

Author(s)

Dimitris Rizopoulos dimitris.rizopoulos@med.kuleuven.be

See Also

rasch

Examples


m <- rasch(Wirs)
vcov(m)
sqrt(diag(vcov(m))) # standard errors


[Package ltm version 0.3-0 Index]