Rasch Modeling of Revised Token Test Performance: Validity and Sensitivity to Change The purpose of this research was to examine the validity of the 55-item Revised Token Test (RTT) and to compare traditional and Rasch-based scores in their ability to detect group differences and change over time. The 55-item RTT was administered to108 left- and right-hemisphere stroke survivors, and the data were ... Research Article
Research Article  |   February 01, 2006
Rasch Modeling of Revised Token Test Performance: Validity and Sensitivity to Change
 
Author Affiliations & Notes
  • William Hula
    VA Pittsburgh Healthcare System, University of Pittsburgh, Pittsburgh, PA
  • Patrick J. Doyle
    VA Pittsburgh Healthcare System, University of Pittsburgh, Pittsburgh, PA
  • Malcolm R. McNeil
    VA Pittsburgh Healthcare System, University of Pittsburgh, Pittsburgh, PA
  • Joseph M. Mikolic
    VA Pittsburgh Healthcare System
  • Contact author: William Hula, VA Pittsburgh Healthcare System, 7180 Highland Drive, 132A-H Pittsburgh, PA 15206. Email: william.hula@med.va.gov
Article Information
Special Populations / Research Issues, Methods & Evidence-Based Practice / Language Disorders / Aphasia / Language / Research Articles
Research Article   |   February 01, 2006
Rasch Modeling of Revised Token Test Performance: Validity and Sensitivity to Change
Journal of Speech, Language, and Hearing Research, February 2006, Vol. 49, 27-46. doi:10.1044/1092-4388(2006/003)
History: Received September 3, 2004 , Accepted May 12, 2005
 
Journal of Speech, Language, and Hearing Research, February 2006, Vol. 49, 27-46. doi:10.1044/1092-4388(2006/003)
History: Received September 3, 2004; Accepted May 12, 2005

The purpose of this research was to examine the validity of the 55-item Revised Token Test (RTT) and to compare traditional and Rasch-based scores in their ability to detect group differences and change over time. The 55-item RTT was administered to108 left- and right-hemisphere stroke survivors, and the data were submitted to Rasch analysis. Traditional and Rasch-based scores for a subsample of 60 stroke survivors were submitted to analyses of variance with group (left hemisphere with aphasia vs. right hemisphere) and time post onset (3 vs. 6 months post onset) as factors. The 2 scoring methods were compared using an index of relative precision. Forty-eight items demonstrated acceptable model fit. Misfitting items came primarily from Subtest IX. The Rasch model accounted for 71% of the variance in the responses to the remaining items. Intersubtest patterns of item difficulty were well predicted by item content, but unexpected within-subtest differences were found. Both traditional and Rasch person scores demonstrated significant group differences, but only the latter demonstrated statistically significant change over time. Analysis of relative precision, however, failed to confirm a significant difference between the 2 methods. The findings generally support the RTT’s validity, but a minority of items appears to respond to a different construct. Also, within-subtest differences in item difficulty suggest the need for further examination of variability in impaired language performance. Finally, the results suggest an equivocal advantage for Rasch scores in detecting change over time.

Acknowledgments
This research was supported by VA Rehabilitation Research and Development Merit Review Projects C2386R and C3159R and the Geriatric Research, Education, and Clinical Center of the VA Pittsburgh Healthcare System. Portions of this article were presented to the 2004 Clinical Aphasiology Conference in Park City, Utah, as part of the 2nd annual Research Symposium in Aphasiology, which was supported by the National Institute on Deafness and Other Communication Disorders. William Hula was supported by a Veterans Health Administration predoctoral fellowship during part of the time that he worked on the project.
We gratefully acknowledge the assistance and support of Katherine Ross and Steven Larson, VA Medical Center (VAMC) Phoenix, AZ; Julie Wambaugh, Rosalea Cameron, Christina Nessler, and Sandra Wright, VAMC Salt Lake City, UT; and Mary Ann Oakley and Amy Goda, VAMC Pittsburgh, PA. We also thank Julie Stierwalt for her helpful comments on an earlier version of this article.
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