sep.pars-class {plink} | R Documentation |
The formal S4 class for sep.pars. This class stores a set of separated item parameters and characteristics of these parameters.
a
will be an n x 1 matrix for n items if there are no nomial responce model or multiple-choice
model items. Otherwise, if nrm or mcm items are included, a
will be an n x m matrix with m
equal to the maximum number of response categories across items. If nrm or mcm items are included,
the discrimination parameters for the dictomous response models, the graded response model, partial
credit model and generalized partial credit model are listed in the first column will all other
columns filled with NA
s.
b
is an n x m matrix of difficulty, threshold, step, or category parameters (depending on the
corresponding model) for n items with m equal to the maximum number of b
parameters across
all items. For items with b
less than m, the row is right-filled with NA
s.
c
will be an n x 1 matrix for n items if there are no multiple-choice model items. Otherwise,
if mcm items are included, c
will be an n x m matrix with m equal to the maximum number of
response categories across items minus one. If mcm items are included, the lower asmptote parameters
for the dictomous response models, are listed in the first column will all other columns filled with
NA
s. The c
values for the 1PL and 2PL equal zero.
Objects can be created by calls of the form new("sep.pars", ...)
, but this is
not encouraged. Use the function sep.pars
instead.
a
:b
:c
:c
is equal to
NA
for each item for all other models.cat
:cat
values equal to 2. Graded response model and
partial credit/generalized partial credit model items will have cat
values equal
to the number of step/threshold parameters plus one. Nominal response model items will
have cat
values equal to the number of categories, and multiple-choice model items
will have cat
values equal to the number of categories plus one (the 'do not know'
category). n
:mod.lab
:loc.out
:TRUE
, the step and/or threshold parameters in
slot b
for the graded response model and generalized partial credit model include a
location parameter. model
:drm, gpcm, grm, mcm, and nrm
(see class "poly.mod"
for more information).items
:model
, where each element identifies
the items(rows) in the corresponding set of item parameters associated with the model(s)
identified in model
.
Class "poly.mod"
, directly.
Class "list.poly"
, by class "poly.mod", distance 2.
Jonathan P. Weeks weeksjp@gmail.com