title: Quantifying practice effects in longitudinal research with the WISC-R and WAIS-R: a study of children and adolescents with hemophilia and male siblings without hemophilia.
abstract: OBJECTIVE
  To quantify practice effects associated with annual administrations of WISC-R and WAIS-R in children and adolescents with and without hemophilia.
  
  
  METHODS
  Participants were young men (age: 7-19; 80 with hemophilia, 30 siblings) enrolled in the Hemophilia Growth and Development Study. Participants with hemophilia completed age-appropriate Wechsler scales at baseline and at four annual follow-ups; the siblings, at baseline and one 2-year follow-up. Regression analyses were used to quantify average changes in scores, adjusting for variables related to test performance.
  
  
  RESULTS
  Consecutive annual evaluations were free of significant practice effects for 4 years with the Verbal Scale and for 2 years with the Performance Scale. VIQ decreased, and PIQ increased over time. Baseline VIQ was related to changes in VIQ; baseline PIQ and number of test-specific retests were related to changes in PIQ.
  
  
  CONCLUSIONS
  The findings support use of Wechsler scales for annual evaluations to monitor cognitive development in children and adolescents.
authors.affiliation: Department of Pediatrics, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA. psirois@tulane.edu
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Sirois
authors.forename: Michael
authors.initials: M
authors.lastname: Posner
authors.forename: James A
authors.initials: JA
authors.lastname: Stehbens
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Loveland
authors.forename: Sharon
authors.initials: S
authors.lastname: Nichols
authors.forename: Sharyne M
authors.initials: SM
authors.lastname: Donfield
authors.forename: Terece S
authors.initials: TS
authors.lastname: Bell
authors.forename: Suzanne D
authors.initials: SD
authors.lastname: Hill
authors.forename: Nancy
authors.initials: N
authors.lastname: Amodei
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002657:Child Development; D002908:Chronic Disease; D006467:Hemophilia A / Q000523:psychology*; D006801:Humans; D007360:Intelligence; D008137:Longitudinal Studies; D008297:Male; D009679:Nuclear Family; D011214:Practice, Psychological; D011594:Psychometrics; D015203:Reproducibility of Results; D014888:Wechsler Scales