Usage
discrpar(object, ...) "discrpar"(object, ref = NULL, alias = TRUE, vcov = TRUE, ...) "discrpar"(object, ref = NULL, alias = TRUE, vcov = TRUE, ...) "discrpar"(object, ref = NULL, alias = TRUE, vcov = TRUE, ...)
Arguments
object
a fitted model object whose discrimination parameters
should be extracted.
ref
a restriction to be used to ensure parameter
identifiability of the item discrimination parameters. Currently not
used as the item discrimination parameters are fixed to unity in
raschmodel
's, rsmodel
's and pcmodel
's.
alias
logical. If TRUE
(the default), the aliased
parameters are included in the return vector (and in the
variance-covariance matrix if vcov
= TRUE). If FALSE
, these
parameters are removed. For raschmodel
's, rsmodel
's
and pcmodel
's where all item discrimination parameters are
fixed to unity, this means that an empty numeric vector and an empty
variance-covariace matrix is returned if alias
is FALSE
.
vcov
logical. If TRUE
(the default), the
variance-covariance matrix of the discrimination parameters is
attached as attribute vcov
.
...
further arguments which are currently not used.