title: Matching variables for research involving youth with Down syndrome: Leiter-R versus PPVT-4.
abstract: Much of what is known about the cognitive profile of Down syndrome (DS) is based on using either receptive vocabulary (e.g., PPTV-4) or nonverbal ability (e.g., Leiter-R) as a baseline to represent cognitive developmental level. In the present study, we examined the relation between these two measures in youth with DS, with non-DS intellectual disability (ID), and with typical development (TD). We also examined the degree to which these two measures produce similar results when used as a group matching variable. In a cross-sectional developmental trajectory analysis, we found that the relation between PPVT-4 and Leiter-R was largely similar across groups. However, when contrasting PPVT-4 and Leiter-R as alternate matching variables, the pattern of results was not always the same. When matched on Leiter-R or PPVT-4, the group with DS performed below that of the groups with ID and TD on receptive grammar and below the group with TD on category learning. When matched on the PPVT-4, the group with ID performed below that of the group with TD on receptive grammar and category learning, but these differences between the groups with ID and TD were not found when matched on the Leiter-R. The results of the study suggest that the PPVT-4 and Leiter-R are interchangeable at least for some outcome measures for comparing youth with DS and TD, but they may produce different results when comparing youth with ID and TD.
authors.affiliation: Department of Psychology, University of Alabama, Box 870348, Tuscaloosa, AL 35487-0348, United States. Electronic address: bashelton1@crimson.ua.edu.
authors.forename: B Allyson
authors.initials: BA
authors.lastname: Phillips
authors.affiliation: Department of Psychology, University of Alabama, Box 870348, Tuscaloosa, AL 35487-0348, United States; Life Span Institute, University of Kansas, 1000 Sunnyside Ave., Lawrence, KS 66045, United States.
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Loveall
authors.affiliation: Department of Psychology, University of Alabama, Box 870348, Tuscaloosa, AL 35487-0348, United States; MIND Institute, University of California, Davis, 2825 50(th) St., Sacramento, CA 95817, United States.
authors.forename: Marie Moore
authors.initials: MM
authors.lastname: Channell
authors.affiliation: Department of Psychology, University of Alabama, Box 870348, Tuscaloosa, AL 35487-0348, United States.
authors.forename: Frances A
authors.initials: FA
authors.lastname: Conners
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D004314:Down Syndrome / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000503:physiopathology* / Q000523:psychology; D007807:Language Tests; D008297:Male; D009633:Nonverbal Communication; D014825:Vocabulary; D055815:Young Adult
keywords: Down syndrome; matching variables; nonverbal ability; receptive vocabulary