as.poly.mod {plink}R Documentation

poly.mod objects

Description

This function attempts to turn the given values into a poly.mod object

Usage

as.poly.mod(n, model = "drm", items = NULL)

Arguments

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 explantion of the codes.
items list identifying the item numbers from a set of parameters that correspond to the given model in model.

Details

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 associted with the codes:

drm:
dichotomous reponse models (includes 1PL, 2PL, and 3PL)
gpcm:
generalized partial credit model (includes the partial credit model)
grm:
graded response model
mcm:
multiple-choice model
nrm:
nominal response model

Value

Returns an object of class poly.mod

Author(s)

Jonathan P. Weeks weeksjp@gmail.com

See Also

poly.mod

Examples

# 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) )

[Package plink version 0.1-1 Index]