title: A quantitative measure of restricted and repetitive behaviors for early childhood.
abstract: BACKGROUND
  Restricted and repetitive behaviors are characteristic phenotypic features of many neurodevelopmental, psychiatric, and neurological conditions. During early childhood, such behaviors are considered normative. More research is needed to delineate the dimensions of restricted and repetitive behavior across typical and atypical development during this period.
  
  
  METHODS
  We developed the 34-item parent-rated Repetitive Behavior Scale for Early Childhood (RBS-EC) to capture quantitative, dimensional features across a broad range of behaviors contributing to this domain. We evaluated its psychometric properties and factor structure in a community sample of 914 toddlers.
  
  
  RESULTS
  The RBS-EC showed excellent overall internal consistency (α = 0.90), strong test-retest reliability (ICC = 0.87 for topographies and 0.90 for frequency) and evidence of convergent and discriminative validity. Using a split-half approach to factor analysis, we identified that a three- or four-factor structure best fit the data and confirmatory factor analysis indicated acceptable fit for both models. The empirically derived four-factor model was consistent with our conceptual model and included repetitive motor, restricted interests and behavior, ritual and routine, and self-directed behavior.
  
  
  CONCLUSIONS
  This initial study indicates that the RBS-EC is a reliable and valid instrument for characterizing quantitative, dimensional aspects of restricted and repetitive behaviors in young children.
authors.affiliation: Department of Educational Psychology, University of Minnesota, Minneapolis, MN USA.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Wolff
authors.affiliation: Department of Allied Health Sciences, University of North Carolina, Chapel Hill, NC USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Boyd
authors.affiliation: Institute of Child Development, University of Minnesota, Minneapolis, MN USA.
authors.forename: Jed T
authors.initials: JT
authors.lastname: Elison
keywords: Circumscribed interests; Measurement; Motor stereotypy; Repetitive behavior; Ritualistic behavior; Self-injurious behavior; Toddlers