title: An introduction to item response theory for health behavior researchers.
abstract: OBJECTIVE
  To introduce item response theory (IRT) to health behavior researchers by contrasting it with classical test theory and providing an example of IRT in health behavior.
  
  
  METHODS
  Demonstrate IRT by fitting the 2PL model to substance-use survey data from the Adolescent  Health Risk Behavior questionnaire (n=1343 adolescents).
  
  
  RESULTS
  An IRT 2PL model can produce viable substance use scores that differentiate different levels of substance use, resulting in improved precision and specificity at the respondent level.
  
  
  CONCLUSIONS
  IRT is a viable  option for health researchers who want to produce high-quality scores for unidimensional constructs. The results from our example-although not flawless-demonstrate the feasibility of IRT in health behavior research.
authors.affiliation: Department of Health Promotion & Behavior, College of Public Health, University of Georgia, Athens, GA, USA. rwarne@uvu.edu
authors.forename: Russell T
authors.initials: RT
authors.lastname: Warne
authors.forename: E J Lisako
authors.initials: EJ
authors.lastname: McKyer
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology; D003625:Data Collection / Q000379:methods / Q000706:statistics & numerical data*; D055030:Drug Users / Q000523:psychology* / Q000706:statistics & numerical data*; D015438:Health Behavior; D006801:Humans; D015233:Models, Statistical; D011582:Psychological Theory; D057566:Self Report