Item Response Theory Modeling of the Philadelphia Naming Test Purpose In this study, we investigated the fit of the Philadelphia Naming Test (PNT; Roach, Schwartz, Martin, Grewal, & Brecher, 1996) to an item-response-theory measurement model, estimated the precision of the resulting scores and item parameters, and provided a theoretical rationale for the interpretation of PNT overall scores by relating ... Research Article
Research Article  |   June 01, 2015
Item Response Theory Modeling of the Philadelphia Naming Test
 
Author Affiliations & Notes
  • Gerasimos Fergadiotis
    Portland State University, OR
  • Stacey Kellough
    Geriatric Research Education and Clinical Center, VA Pittsburgh Healthcare System, PA
  • William D. Hula
    Geriatric Research Education and Clinical Center, VA Pittsburgh Healthcare System, PA
    University of Pittsburgh, PA
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication.×
  • Correspondence to Gerasimos Fergadiotis: gfergadiotis@pdx.edu
  • This article is a companion to Hula et al., “Development and Simulation Testing of a Computerized Adaptive Version of the Philadelphia Naming Test,” JSLHR, doi:10.1044/2015_JSLHR-L-14-0297
    This article is a companion to Hula et al., “Development and Simulation Testing of a Computerized Adaptive Version of the Philadelphia Naming Test,” JSLHR, doi:10.1044/2015_JSLHR-L-14-0297×
  • Editor: Rhea Paul
    Editor: Rhea Paul×
  • Associate Editor: Swathi Kiran
    Associate Editor: Swathi Kiran×
Article Information
Research Issues, Methods & Evidence-Based Practice / Language / Research Articles
Research Article   |   June 01, 2015
Item Response Theory Modeling of the Philadelphia Naming Test
Journal of Speech, Language, and Hearing Research, June 2015, Vol. 58, 865-877. doi:10.1044/2015_JSLHR-L-14-0249
History: Received September 5, 2014 , Revised January 6, 2015 , Accepted February 15, 2015
 
Journal of Speech, Language, and Hearing Research, June 2015, Vol. 58, 865-877. doi:10.1044/2015_JSLHR-L-14-0249
History: Received September 5, 2014; Revised January 6, 2015; Accepted February 15, 2015
Web of Science® Times Cited: 1

Purpose In this study, we investigated the fit of the Philadelphia Naming Test (PNT; Roach, Schwartz, Martin, Grewal, & Brecher, 1996) to an item-response-theory measurement model, estimated the precision of the resulting scores and item parameters, and provided a theoretical rationale for the interpretation of PNT overall scores by relating explanatory variables to item difficulty. This article describes the statistical model underlying the computer adaptive PNT presented in a companion article (Hula, Kellough, & Fergadiotis, 2015).

Method Using archival data, we evaluated the fit of the PNT to 1- and 2-parameter logistic models and examined the precision of the resulting parameter estimates. We regressed the item difficulty estimates on three predictor variables: word length, age of acquisition, and contextual diversity.

Results The 2-parameter logistic model demonstrated marginally better fit, but the fit of the 1-parameter logistic model was adequate. Precision was excellent for both person ability and item difficulty estimates. Word length, age of acquisition, and contextual diversity all independently contributed to variance in item difficulty.

Conclusions Item-response-theory methods can be productively used to analyze and quantify anomia severity in aphasia. Regression of item difficulty on lexical variables supported the validity of the PNT and interpretation of anomia severity scores in the context of current word-finding models.

Acknowledgments
This research was supported by VA Rehabilitation Research and Development Career Development Award C7476W (awarded to William Hula) and the VA Pittsburgh Healthcare System Geriatric Research Education and Clinical Center. The authors would like to acknowledge the helpful assistance of Daniel Mirman and Myrna Schwartz. The contents of this article do not represent the views of the Department of Veterans Affairs or the United States government.
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