Individual Part Score Profiles of Children With Intellectual Disability: A Descriptive Analysis Across Three Intelligence Tests

Abstract.

This study examined the group- and individual-level part score profiles of children with intellectual disability (ID) who participated in clinical validity studies supporting three individually administered intelligence tests. Across tests, children with ID produced group-level profiles comprising mean part scores that fell in the Low to Very Low ranges. However, profile similarity analysis revealed that few of these children exhibited profiles similar to their respective group-level profile. When profiles of individual children were examined, 7% to 17% obtained at least one part score in the Average range or higher (standard score ≥ 90), and 33% to 52% obtained at least one part score in the Low Average range or higher (standard score ≥ 80). Moreover, the percentage of children who would not be identified as having ID based on elevated part scores ranged between 33% and 80%. Based on these results and considering the diagnostic criteria for ID, deferring diagnosis and denying services to children who meet all criteria for ID but who have elevated part scores yielded from valid testing, when there is no diagnosis or eligibility category better describing the impairing condition, appears to be a flawed and inappropriate practice.

Notes

The authors are thankful for the provision of Differential Ability Scales—Second Edition II and Wechsler Intelligence Scale for Children—Fourth Edition clinical data sets by NCS Pearson, Inc., and appreciate Lawrence Weiss, William Schryver, and Ying Meng for their support and assistance during this process. In addition, we thank Marshall Dahl and Scott Overgaard (while at American Guidance Service) for originally providing the Kaufman Assessment Battery for Children—Second Edition clinical data set. The authors are appreciative of the feedback from Sarah Irby, Ruben Lopez, John Nomura, and Matt Reynolds about drafts of this article and influenced by the National Association of School Psychology listerv and Institute for Applied Psychometrics Cattell–Horn–Carroll listserv posts made by Mike Arm, Gary Canivez, Rhonda Cash, Cathy Fiorello, Dawn Flanagan, Robert Misak, John Nomura, Ruben Lopez, Guy McBride, Cecil Reynolds, and Joel Schneider about this topic. Communications with Kevin McGrew over the past decade greatly shaped this study.

Standardization data from the Differential Ability Scales—Second Edition. Copyright © 2007 by NCS Pearson, Inc. Used with permission. All rights reserved. Standardization data from the Kaufman Assessment Battery for Children—Second Edition. Copyright © 2004 by NCS Pearson, Inc. Used with permission. All rights reserved. Standardization data from the Wechsler Intelligence Scale for Children-Fourth Edition. Copyright © 2003 by NCS Pearson, Inc. Used with permission. All rights reserved.

Additional information

Notes on contributors

Renee Bergeron

Renee Bergeron is a school psychologist with the Hawaii Department of Education. She received her doctoral degree from The University of Memphis in 2006. Her research interests are in the areas of cognitive and behavioral assessment.

Randy G. Floyd

Randy G. Floyd is an asssociate professor of psychology at The University of Memphis. He received his doctoral degree in school psychology from Indiana State University in 1999. His research interests include the structure, measurement, and correlates of cognitive abilities; the technical properties of early numeracy measures; and the process of professional publication. He is the editor of the Journal of School Psychology.