plink-package: IRT Separate Calibration Linking Methods

Description Details Author(s) References


This package uses unidimensional and multidimensional item response theory methods to compute linking constants and conduct chain linking of tests for multiple groups under a nonequivalent groups common item design.


The package consists of three types of functions:

Running the separate calibration is typically a two-step process. The first step is to format the item parameters and the second step is to run the function plink. In the simplest scenario, the parameters should be formatted as a single object with multiple groups. Refer to the function for specific details. Once in this format, the linking constants can be computed using plink. The summary function can be used to summarize the common item parameters (including descriptive statistics) and the linking constants.

To compute response probabilities for a given model, the following functions can be used: drm, gpcm, grm, mcm, or nrm. The plot function can be used to create item/category characteristic curves, item/category response surfaces, and vector plots.


Jonathan P. Weeks


Weeks, J. P. (2010) plink: An R package for linking mixed-format tests using IRT-based methods. Journal of Statistical Software, 35(12), 1–33. URL

plink documentation built on May 1, 2019, 8:07 p.m.