A Collection of Functions Related to Item Response Theory (IRT)

A collection of functions useful in learning and practicing IRT, which can be combined into larger programs. Provides basic CTT analysis, a simple common interface to the estimation of item parameters in IRT models for binary responses with three different programs (ICL, BILOG-MG, and ltm), ability estimation (MLE, BME, EAP, WLE, plausible values), item and person fit statistics, scaling methods (MM, MS, Stocking-Lord, and the complete Hebaera method), and a rich array of parametric and non-parametric (kernel) plots. Estimates and plots Haberman's interaction model when all items are dichotomously scored.


New in 0.2.1

Nothing, really, except that I had to provide new links to the ICL files as a result of Dropbox's new policy on shared files. God bless Brad's beautiful soul, 15 years dead and still helping us.

New in 0.2.0

  • Added functions to estimate and plot the interaction model

  • Added erf, a function to plot the empirical item response function

  • Added ssm, a function to produce IRF in the sum score metric

  • Added ifp, a function to plot IRF with error bounds.

  • Small improvements in the tia function

  • Links to download Brad Hanson's ICL program (see the package help page)

      	      CHANGES IN irtoys VERSION 0.1.7


o new function, tet(), to calculate, quickly, an approximate matrix of tetrachoric correlations.


o fixed a bug in function wle() which affected the variance of Warm's weighted estimate of ability in the case of the 3PL model only.

Reference manual

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0.2.1 by Ivailo Partchev, a year ago

Browse source code at https://github.com/cran/irtoys

Authors: Ivailo Partchev [aut, cre] , Gunter Maris [aut] , Tamaki Hattori [ctb]

Documentation:   PDF Manual  

Task views: Psychometric Models and Methods

GPL (>= 2) license

Depends on sm, ltm

Suggests MASS, knitr

Imported by PerFit, PsyControl.

Depended on by subscore.

Suggested by PLmixed, RndTexExams, catIrt.

See at CRAN