Usage
threshpar(object, ...) "threshpar"(object, type = c("mode", "median", "mean"), ref = NULL, alias = TRUE, relative = FALSE, cumulative = FALSE, vcov = TRUE, ...) "threshpar"(object, type = c("mode", "median", "mean"), ref = NULL, alias = TRUE, relative = FALSE, cumulative = FALSE, vcov = TRUE, ...) "threshpar"(object, type = c("mode", "median", "mean"), ref = NULL, alias = TRUE, relative = FALSE, cumulative = FALSE, vcov = TRUE, ...)
Arguments
object
a fitted model object whose threshold parameters
should be extracted.
type
character of length one which determines the type of
threshold parameters to return (see details below).
ref
a vector of labels or position indices of (relative)
threshold parameters or a contrast matrix which should be used
as restriction/for normalization. For partial credit models,
argument ref
can also be a list of m contrasts. If
NULL
(the default), the relative threshold parameters
are centered around their item-specific means and the absolute
threshold parameters are centered around their global mean.
alias
logical. If TRUE
(the default), the aliased
parameter is included in the return vector (and in the variance-covariance
matrix if vcov
= TRUE). If FALSE
, it is removed. If the
restriction given in ref
depends on several parameters, the
first parameter of the restriction specified is (arbitrarily) chosen
to be removed if alias
is FALSE
.
relative
logical. If set to FALSE
(default), absolute item
threshold parameters are returned. If set to TRUE
, relative
item threshold parameters with the contrast specified
in argument ref
are returned.
cumulative
logical. If set to TRUE
, cumulative threshold
parameters are returned. These correspond to the cumulative sum over
the absolute or relative item threshold parameters (after the
restriction given in argument ref
has been applied).
vcov
logical. If TRUE
(the default), the (transformed)
variance-covariance matrix of the (relative) threshold parameters
is attached as attribute vcov
.. If FALSE
, a NA-matrix
is attached.
...
further arguments which are currently not used.