title: The problem of matching.
authors.affiliation: University of Colorado, School of Medicine, Denver, USA.
authors.forename: B
authors.initials: B
authors.lastname: Camp
mesh_terms: D002648:Child; D002652:Child Behavior; D002675:Child, Preschool; D006801:Humans; D016555:Matched-Pair Analysis; D010372:Pediatrics; D012106:Research