title: A hierarchy of distress: Mokken scaling of the GHQ-30.
abstract: BACKGROUND
  Hierarchical cumulative scales are common and informative in psychology. The General Health Questionnaire (GHQ) does not appear to have been subjected to an analysis that examines the hierarchical and cumulative nature of its items. We report an analysis of data from the 30-item GHQ (GHQ-30) as part of the Health and Lifestyle Survey (HALS).
  
  
  METHODS
  Data from 6317 participants who completed the GHQ-30 as part of the HALS were analysed using the Mokken Scaling Procedure (MSP), which is a computer program that searches polychotomous data for hierarchical and cumulative scales on the basis of a range of diagnostic criteria.
  
  
  RESULTS
  A final scale consisting of nine items from the GHQ-30 was obtained that, according to the criteria for a Mokken scale, was a reliable and very strong scale. The least difficult item in the scale is 'been (un)able to face up to your problems?' and the most difficult item is 'felt that life isn't worth living?'
  
  
  CONCLUSIONS
  Items from the GHQ-30 form a short hierarchical and cumulative scale. The majority of these items also appear in the GHQ-12. The nine-item GHQ shows better distribution properties than the GHQ-30 and compares very favourably with the GHQ-12.
authors.affiliation: School of Nursing and Midwifery, The University of Sheffield, UK. roger.watson@sheffield.ac.uk
authors.forename: R
authors.initials: R
authors.lastname: Watson
authors.forename: I J
authors.initials: IJ
authors.lastname: Deary
authors.forename: B
authors.initials: B
authors.lastname: Shipley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001008:Anxiety Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D003866:Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008403:Mass Screening; D008432:Mathematical Computing; D008875:Middle Aged; D010555:Personality Inventory / Q000706:statistics & numerical data*; D011594:Psychometrics / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D012917:Social Adjustment; D006113:United Kingdom