plink-package {plink} | R Documentation |
This package uses item response theory methods to compute linking constants and conduct chain linking of tests for multiple groups under a nonequivalent groups common item design. It allows for mean/mean, mean/sigma, Haebara, and Stocking-Lord calibrations of dichotomous (1PL, 2PL, and 3PL) and/or polytomous (graded response, partial credit/generalized partial credit, nominal, and multiple-choice model) common items.
Running the separate calibration is typically a two-step process. The first step is to
format the item parameters for processing with plink
. Parameters should be formatted
as a single irt.pars
object with multiple groups, a set of irt.pars
objects, or a set of sep.pars
object. Once in this format, response
probabilities can be computed using drm, gpcm, grm, mcm, or nrm
or linking constants
can be computed using plink
.
The functions as.irt.pars
, sep.pars
, and combine.pars
can be used to create the irt.pars
and sep.pars
objects. The function summary
can be used to summarize item parameters (including descriptive statistics) and linking constants,
and plot
can be used to create item/category characteristic curves.
Jonathan P. Weeks weeksjp@gmail.com