title: An international scoring system for self-reported health complaints in adolescents.
abstract: BACKGROUND
  Aimed to develop a unitary scoring system for the 'Health Behaviour in school-aged Children' (HBSC) symptom checklist that would facilitate cross-national comparisons and interpretation. Rasch measurement analysis and investigation of differential item functioning (DIF) were conducted.
  
  
  METHODS
  Data were obtained from the 'WHO collaborative study HBSC 2001/2002'. A total of 162,305 students aged 11, 13 and 15 years from 35 European and North American Countries were surveyed. Unidimensionality of the items and local independence were tested using means of confirmatory factor analysis. DIF across countries, age groups and gender was investigated using a logistic regression procedure. Item and person parameters were estimated according to the Rating Scale Model (RSM).
  
  
  RESULTS
  All items proved to be unidimensional. One item displayed noticeable DIF across countries and was discarded. The remaining items were functioning equally across subgroups. The RSM analysis resulted in Rasch model conform item parameter estimation. Infit mean square values between 0.84 and 1.35 revealed acceptable item fit.
  
  
  CONCLUSIONS
  The control of DIF enables comparable and unbiased assessment of subjective health complaints across countries, age groups and gender. A scoring algorithm could be developed which enables a cross-cultural comparable and interval-scaled assessment of subjective health complaints.
authors.affiliation: School of Public Health, WHO Collaborating Center for Child and Adolescent Health Promotion, University of Bielefeld, Germany. U.Ravens-Sieberer@uni-bielefeld.de
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ravens-Sieberer
authors.forename: Michael
authors.initials: M
authors.lastname: Erhart
authors.forename: Torbjorn
authors.initials: T
authors.lastname: Torsheim
authors.forename: Jorn
authors.initials: J
authors.lastname: Hetland
authors.forename: John
authors.initials: J
authors.lastname: Freeman
authors.forename: Mia
authors.initials: M
authors.lastname: Danielson
authors.forename: Christiane
authors.initials: C
authors.lastname: Thomas
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000295:Adolescent Medicine / Q000379:methods*; D000352:Africa, Northern; D002648:Child; D003431:Cross-Cultural Comparison; D003627:Data Interpretation, Statistical; D005060:Europe; D005260:Female; D006306:Health Surveys; D006801:Humans; D016015:Logistic Models; D008297:Male; D025341:Principal Component Analysis; D000297:Psychology, Adolescent; D011594:Psychometrics; D015203:Reproducibility of Results; D012650:Self Disclosure; D012720:Severity of Illness Index; D014944:World Health Organization