Tutorial  |   August 2011
An Introduction to Item Response Theory and Rasch Models for Speech-Language Pathologists
Author Affiliations & Notes
  • William Hula
    VA Pittsburgh Healthcare System Geriatric Research Education and Clinical Center, and University of Pittsburgh, PA
  • Neila J. Donovan
    Louisiana State University, Baton Rouge
  • Patrick J. Doyle
    VA Pittsburgh Healthcare System Geriatric Research Education and Clinical Center, and University of Pittsburgh, PA
  • Diane Kendall
    University of Washington, Seattle
  • Kathryn Yorkston
    University of Washington, Seattle
  • Correspondence to Carolyn Baylor: cbaylor@u.washington.edu
  • Editor and Associate Editor: Laura Justice
    Editor and Associate Editor: Laura Justice×
Article Information
Speech, Voice & Prosodic Disorders / Research Issues, Methods & Evidence-Based Practice / Normal Language Processing / Language Disorders / Tutorial
Tutorial   |   August 2011
An Introduction to Item Response Theory and Rasch Models for Speech-Language Pathologists
American Journal of Speech-Language Pathology, August 2011, Vol. 20, 243-259. doi:10.1044/1058-0360(2011/10-0079)
History: Received September 10, 2010 , Revised February 10, 2011 , Accepted April 25, 2011
American Journal of Speech-Language Pathology, August 2011, Vol. 20, 243-259. doi:10.1044/1058-0360(2011/10-0079)
History: Received September 10, 2010; Revised February 10, 2011; Accepted April 25, 2011
Web of Science® Times Cited: 7

Purpose: To present a primarily conceptual introduction to item response theory (IRT) and Rasch models for speech-language pathologists (SLPs).

Method: This tutorial introduces SLPs to basic concepts and terminology related to IRT as well as the most common IRT models. The article then continues with an overview of how instruments are developed using IRT and some basic principles of adaptive testing.

Conclusion: IRT is a set of statistical methods that are increasingly used for developing instruments in speech-language pathology. While IRT is not new, its application in speech-language pathology to date has been relatively limited in scope. Several new IRT-based instruments are currently emerging. IRT differs from traditional methods for test development, typically referred to as classical test theory (CTT), in several theoretical and practical ways. Administration, scoring, and interpretation of IRT instruments are different from methods used for most traditional CTT instruments. SLPs will need to understand the basic concepts of IRT instruments to use these tools in their clinical and research work. This article provides an introduction to IRT concepts drawing on examples from speech-language pathology.

Acknowledgments
This project was supported in part by National Institute on Deafness and Other Communication Disorders Grant 1R03DC010044 (Baylor), VA Rehabilitation Research and Development Career Development Award C6210M (Hula), VA RR&D Merit Review Project C6098R (Doyle), and Louisiana Board of Regents Research Competitiveness Project LESQSF(2008-11)-RD-A-07 (Donovan). We gratefully acknowledge the assistance of Clement Stone, who provided comments on an earlier draft of this article.
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