vcov {ltm} | R Documentation |
Extracts the asymptotic variance-covariance matrix of the MLEs from either grm
,
ltm
, rasch
or tpm
objects.
## S3 method for class 'grm': vcov(object, ...) ## S3 method for class 'ltm': vcov(object, robust = FALSE, ...) ## S3 method for class 'rasch': vcov(object, robust = FALSE, ...) ## S3 method for class 'tpm': vcov(object, ...)
object |
an object inheriting from either class grm , class ltm , class rasch or class tpm . |
robust |
logical; if TRUE the sandwich estimator is used. |
... |
additional arguments; currently none is used. |
a numeric matrix representing the estimated covariance matrix of the maximum likelihood estimates.
Dimitris Rizopoulos dimitris.rizopoulos@med.kuleuven.be
fit <- rasch(WIRS) vcov(fit) sqrt(diag(vcov(fit))) # standard errors