title: The Manual Work Instability Scale: development and validation.
abstract: BACKGROUND
  Increasing awareness of the burden of absenteeism and reduced performance at work highlights the importance of early identification of individuals experiencing work instability (WI), a mismatch between functional and cognitive abilities and job demands.
  
  
  OBJECTIVE
  To develop and validate a screening questionnaire to measure WI in manual workers.
  
  
  METHODS
  Questionnaire items were generated via qualitative interviews with manual workers and a draft survey instrument was completed by workers in a variety of fields. Rasch analysis was used interactively to assess the psychometric aspects of the emerging scale, including unidimensionality and absence of item bias (differential item functioning).
  
  
  RESULTS
  A total of 17 qualitative interviews generated 110 potential items for the questionnaire. The item set resolved to a 25-item scale, which satisfied model expectations (item residual mean = -0.13, SD = 1.04; person residual mean = -0.29, SD = 0.75), had good reliability (alpha = 0.86) and strict unidimensionality (t-test 7.5% confidence interval 3.8-11.2).
  
  
  CONCLUSIONS
  The Manual Work Instability Scale is a short psychometrically robust questionnaire based on the concept of WI, which incorporates both musculoskeletal symptoms and relevant psychosocial factors. It may prove effective in screening and identifying WI in workers in predominantly physical occupations.
authors.affiliation: Department of Rehabilitation Medicine, Faculty of Medicine and Health, The University of Leeds, D Floor, Martin Wing, The General Infirmary at Leeds, Gt. George Street, Leeds, West Yorkshire LS1 3EX, UK.
authors.forename: G
authors.initials: G
authors.lastname: Gilworth
authors.affiliation: Work Fit Occupational Physiotherapy and Ergonomics Services Ltd., 38 Newlay Lane, Leeds, West Yorkshire LS18 4LE, UK.
authors.forename: M G
authors.initials: MG
authors.lastname: Smyth
authors.affiliation: Work Fit Occupational Physiotherapy and Ergonomics Services Ltd., 38 Newlay Lane, Leeds, West Yorkshire LS18 4LE, UK.
authors.forename: J
authors.initials: J
authors.lastname: Smith
authors.affiliation: Schweizer Paraplegiker-Forschung AG, Guido A. Zäch Strasse 4, 6207 Nottwil, Switzerland. alan.tennant@paraplegie.ch.
authors.forename: A
authors.initials: A
authors.lastname: Tennant
mesh_terms: D000041:Absenteeism; D000328:Adult; D004651:Employment / Q000145:classification / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011594:Psychometrics / Q000295:instrumentation* / Q000379:methods; D036301:Qualitative Research; D015203:Reproducibility of Results; D062707:Return to Work / Q000639:trends; D011795:Surveys and Questionnaires; D014938:Work Capacity Evaluation
keywords: Manual workers; Rasch analysis; screening questionnaire; work instability.