title: Relative age effects in the Movement Assessment Battery for Children-2: age banding and scoring errors.
abstract: The Movement Assessment Battery for Children-2 (MABC-2) uses age-grouped scoring, which will result in relative motor functioning being overestimated for some children and underestimated for others. In this paper, we measure these errors and discuss their consequences.
  
  
  
  We pool data from two validation studies to obtain a sample of 278 children assessed with the MABC-2 (mean (SD) age: 5 years, 0 months (9.6 months); 142 female). We used regression to measure the association between standard score and relative age, and used these results to estimate misclassification rates at the MABC-2's recommended thresholds.
  
  
  
  Movement Assessment Battery for Children-2 scores were distributed as expected (mean (SD) = 10.4 (2.8)). We estimated that the standard score varied by 2.76 units (0.92 SDs) per year of relative age. Depending on threshold and age bandwidth, this implies overall misclassification rates from 9% to 23%.
  
  
  
  Relative age differences in MABC-2 scores led to substantial systematic error for young children. These errors can affect MABC-2 validity, longitudinal stability and agreement with other tools, which may reduce the appropriateness of care offered to children. Scoring approaches that may reduce or eliminate these errors are outlined.
authors.affiliation: Infant and Child Health (INCH) Lab, Department of Family Medicine, McMaster University, Hamilton, ON, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Veldhuizen
authors.affiliation: CanChild Centre for Studies in Childhood Disability, McMaster University, Hamilton, Canada.
authors.forename: L
authors.initials: L
authors.lastname: Rivard
authors.affiliation: Infant and Child Health (INCH) Lab, Department of Family Medicine, McMaster University, Hamilton, ON, Canada.|Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Cairney
mesh_terms: D000367:Age Factors; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D019957:Motor Skills Disorders / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012107:Research Design; D012720:Severity of Illness Index; D054928:Validation Studies as Topic
keywords: developmental coordination disorder; early assessment; motor coordination; screening