Linking Outcomes From Peabody Picture Vocabulary Test Forms Using Item Response Models PurposeThe present work describes how vocabulary ability as assessed by 3 different forms of the Peabody Picture Vocabulary Test (PPVT; Dunn & Dunn, 1997) can be placed on a common latent metric through item response theory (IRT) modeling, by which valid comparisons of ability between samples or over time can ... Research Note
Research Note  |   June 01, 2012
Linking Outcomes From Peabody Picture Vocabulary Test Forms Using Item Response Models
 
Author Affiliations & Notes
  • Lesa Hoffman
    University of Nebraska—Lincoln
  • Jonathan Templin
    University of Georgia, Athens
  • Mabel L. Rice
    University of Kansas, Lawrence
  • Correspondence to Lesa Hoffman: lhoffman2@unl.edu
  • Editor: Janna Oetting
    Editor: Janna Oetting×
  • Associate Editor: Ron Gillam
    Associate Editor: Ron Gillam×
Article Information
Language
Research Note   |   June 01, 2012
Linking Outcomes From Peabody Picture Vocabulary Test Forms Using Item Response Models
Journal of Speech, Language, and Hearing Research, June 2012, Vol. 55, 754-763. doi:10.1044/1092-4388(2011/10-0216)
History: Received August 6, 2010 , Revised April 21, 2011 , Accepted October 6, 2011
 
Journal of Speech, Language, and Hearing Research, June 2012, Vol. 55, 754-763. doi:10.1044/1092-4388(2011/10-0216)
History: Received August 6, 2010; Revised April 21, 2011; Accepted October 6, 2011
Web of Science® Times Cited: 7

PurposeThe present work describes how vocabulary ability as assessed by 3 different forms of the Peabody Picture Vocabulary Test (PPVT; Dunn & Dunn, 1997) can be placed on a common latent metric through item response theory (IRT) modeling, by which valid comparisons of ability between samples or over time can then be made.

MethodResponses from 2,625 cases in a longitudinal study of 697 persons for 459 unique PPVT items (175 items from Peabody Picture Vocabulary Test—Revised [PPVT–R] Form M [Dunn & Dunn, 1981 ], 201 items from Peabody Picture Vocabulary Test—3 [PPVT–3] Form A [Dunn & Dunn, 1997 ], and 83 items from PPVT–3 Form B [Dunn & Dunn, 1997 ]) were analyzed using a 2-parameter logistic IRT model.

ResultsThe test forms each covered approximately ±3 SDs of vocabulary ability with high reliability. Some differences between item sets in item difficulty and discrimination were found between the PPVT–3 Forms A and B.

ConclusionsComparable estimates of vocabulary ability obtained from different test forms can be created through IRT modeling. The authors have also written a freely available SAS program that uses the obtained item parameters to provide IRT ability estimates given item responses to any of the 3 forms. This scoring resource will allow others with existing PPVT data to benefit from this work as well.

Acknowledgments
This research was funded by National Institutes of Health Grants P30DC005803, R01DC001803, and R01DC005226 (awarded to Mabel L. Rice) and by University of Kansas Intellectual and Developmental Disabilities Research Center Grant P30HD002528. We thank Denise Perpich for data management as well as the research assistants and students in Mabel L. Rice's Language Acquisition Studies Lab at the University of Kansas for data collection and data processing. Finally, we appreciate the time and effort of the children and their families who participated.
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