title: Further validation of the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) in the UK veterinary profession: Rasch analysis.
abstract: OBJECTIVE
  To examine the psychometric properties of the 14-item Warwick-Edinburgh Mental Well-being Scale (WEMWBS) in the UK veterinary profession by the application of Rasch analysis, and to assess the external construct validity of the derived interval scale measurements.
  
  
  METHODS
  Data sets were derived from two independent cross-sectional surveys of the veterinary profession (n = 8,829 and n = 1,796). Rasch analysis (n = 500) included response option thresholds ordering, tests of fit, differential item functioning, targeting, response dependency, and person separation index (PSI). Unidimensionality was evaluated by principal component analysis of residuals. The findings were validated across further subsamples from both data sets. The external construct validity of the Rasch-fitting item set was evaluated by associations with other measures of psychological health or psychosocial work characteristics.
  
  
  RESULTS
  Data for the original 14 items deviated significantly from Rasch model expectations (chi-square = 558.2, df = 112, P = <0.001, PSI = 0.918). A unidimensional 7-item scale (Short WEMWBS, SWEMWBS) with acceptable fit to the model (chi-square = 58.8, df = 56, P = 0.104, PSI = 0.832) was derived by sequential removal of the most misfitting items. The external construct validity of SWEMWBS was supported.
  
  
  CONCLUSIONS
  SWEMWBS has robust interval-level measurement properties which support its suitability as an indicator of population mental health and well-being in this occupational group with elevated suicide risk.
authors.affiliation: Faculty of Medicine, University Department of Psychiatry, University of Southampton, Academic Centre, College Keep, 4-12 Terminus Terrace, Southampton, SO14 3DT, UK. djb1f08@soton.ac.uk
authors.forename: David J
authors.initials: DJ
authors.lastname: Bartram
authors.forename: Julia M
authors.initials: JM
authors.lastname: Sinclair
authors.forename: David S
authors.initials: DS
authors.lastname: Baldwin
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008603:Mental Health; D008875:Middle Aged; D016272:Occupational Health; D010549:Personal Satisfaction; D025341:Principal Component Analysis; D011594:Psychometrics / Q000379:methods*; D011788:Quality of Life / Q000523:psychology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D006113:United Kingdom; D018634:Veterinarians / Q000523:psychology*