Published by the Foundation for Open Access Statistics Editors-in-chief: Bettina Grün, Torsten Hothorn, Edzer Pebesma, Achim Zeileis    ISSN 1548-7660; CODEN JSSOBK
Authors: Dimitris Rizopoulos
Title: ltm: An R Package for Latent Variable Modeling and Item Response Analysis
Abstract: The R package ltm has been developed for the analysis of multivariate dichotomous and polytomous data using latent variable models, under the Item Response Theory approach. For dichotomous data the Rasch, the Two-Parameter Logistic, and Birnbaum's Three-Parameter models have been implemented, whereas for polytomous data Semejima's Graded Response model is available. Parameter estimates are obtained under marginal maximum likelihood using the Gauss-Hermite quadrature rule. The capabilities and features of the package are illustrated using two real data examples.

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Paper: ltm: An R Package for Latent Variable Modeling and Item Response Analysis     Download PDF (Downloads: 38002)
Supplements:
ltm_0.7-0.tar.gz: R source package Download (Downloads: 3174; 73KB)
v17i05.R.zip: v17i05.R: R example code from the paper Download (Downloads: 3422; 1KB)
DOI: 10.18637/jss.v017.i05

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Paper: Creative Commons Attribution 3.0 Unported License
Code: GNU General Public License (at least one of version 2 or version 3) or a GPL-compatible license.