title: An evaluation of computerized adaptive testing for general psychological distress: combining GHQ-12 and Affectometer-2 in an item bank for public mental health research.
abstract: Recent developments in psychometric modeling and technology allow pooling well-validated items from existing instruments into larger item banks and their deployment through methods of computerized adaptive testing (CAT). Use of item response theory-based bifactor methods and integrative data analysis overcomes barriers in cross-instrument comparison. This paper presents the joint calibration of an item bank for researchers keen to investigate population variations in general psychological distress (GPD).
  
  
  
  Multidimensional item response theory was used on existing health survey data from the Scottish Health Education Population Survey (n = 766) to calibrate an item bank consisting of pooled items from the short common mental disorder screen (GHQ-12) and the Affectometer-2 (a measure of "general happiness"). Computer simulation was used to evaluate usefulness and efficacy of its adaptive administration.
  
  
  
  A bifactor model capturing variation across a continuum of population distress (while controlling for artefacts due to item wording) was supported. The numbers of items for different required reliabilities in adaptive administration demonstrated promising efficacy of the proposed item bank.
  
  
  
  Psychometric modeling of the common dimension captured by more than one instrument offers the potential of adaptive testing for GPD using individually sequenced combinations of existing survey items. The potential for linking other item sets with alternative candidate measures of positive mental health is discussed since an optimal item bank may require even more items than these.
authors.affiliation: Department of Health Sciences, University of York, York, UK. js883@cam.ac.uk.|Department of Psychiatry, University of Cambridge, Cambridge Biomedical Campus, Box 189, Cambridge, CB2 0QQ, UK. js883@cam.ac.uk.|Department of Kinanthropology, Charles University, Prague, Czech Republic. js883@cam.ac.uk.
authors.forename: Jan
authors.initials: J
authors.lastname: Stochl
authors.affiliation: Department of Health Sciences, University of York, York, UK.|Hull York Medical School (HYMS), University of York, York, UK.
authors.forename: Jan R
authors.initials: JR
authors.lastname: Böhnke
authors.affiliation: Department of Health Sciences, University of York, York, UK.
authors.forename: Kate E
authors.initials: KE
authors.lastname: Pickett
authors.affiliation: Department of Health Sciences, University of York, York, UK.|Hull York Medical School (HYMS), University of York, York, UK.|Dundee Centre for Health And Related Research, School of Nursing & Health Sciences, University of Dundee and Academic Health Science Partnership Tayside, Dundee, UK.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Croudace
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008960:Models, Psychological; D011594:Psychometrics / Q000379:methods*; D013315:Stress, Psychological / Q000175:diagnosis*
keywords: Affectometer; Computerized adaptive testing; General Health Questionnaire; Item Response Theory