Further validation of the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) in the UK veterinary profession: Rasch analysis

Purpose 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 =