| 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")