as.poly.mod {plink} | R Documentation |
This function attempts to turn the given values into a poly.mod
object that
associates each item with a specific unidimensional or multidimensional item response model.
as.poly.mod(n, model = "drm", items = NULL)
n |
total number of items |
model |
character vector identifying the IRT models used to estimate
the item parameters. The only acceptable models are
drm, gpcm, grm, mcm, and nrm . See below for an explanation of
the codes. |
items |
list identifying the item numbers from a set of parameters
that correspond to the given model in model . |
When creating a poly.mod
object, there is no difference in the specification for
unidimensional versus multidimensional item response models. If all the items are dichotomous,
it is only necessary to specify a value for n
. If all the items correspond to a
single model (other than drm
), only n
and model
need to be specified.
The IRT models associated with the codes:
drm
:gpcm
:grm
:mcm
:nrm
:
Returns an object of class poly.mod
Jonathan P. Weeks weeksjp@gmail.com
# Ten dichotomous items as.poly.mod(10) # The first ten items in the set of associated (not present here) item # parameters are dichotomous and the last five were estimated using the # generalized partial credit model as.poly.mod(15, c("drm", "gpcm"), list(1:10,11:15) ) # Ten multidimensional graded response model items # Note: This same specification would be used for a unidimensional # graded response model as.poly.mod(10, "grm")