title: Responsiveness of the individual work performance questionnaire.
abstract: BACKGROUND
  Individual work performance is an important outcome measure in studies in the workplace. Nevertheless, its conceptualization and measurement has proven challenging. To overcome limitations of existing scales, the Individual Work Performance Questionnaire (IWPQ) was recently developed. The aim of the current study was to gain insight into the responsiveness of the IWPQ.
  
  
  METHODS
  Data were used from the Be Active & Relax randomized controlled trial. The aim of the trial was to investigate the effectiveness of an intervention to stimulate physical activity and relaxation of office workers, on need for recovery. Individual work performance was a secondary outcome measure of the trial. In total, 39 hypotheses were formulated concerning correlations between changes on the IWPQ scales and changes on similar constructs (e.g., presenteeism) and distinct constructs (e.g., need for recovery) used in the trial.
  
  
  RESULTS
  260 Participants completed the IWPQ at both baseline and 12 months of follow-up. For the IWPQ scales, 23%, 15%, and 38%, respectively, of the hypotheses could be confirmed. In general, the correlations between change scores were weaker than expected. Nevertheless, at least 85% of the correlations were in the expected direction.
  
  
  CONCLUSIONS
  Based on results of the current study, no firm conclusions can be drawn about the responsiveness of the IWPQ. Several reasons may account for the weaker than expected correlations. Future research on the IWPQ's responsiveness should be conducted, preferably in other populations and intervention studies, where greater changes over time can be expected.
authors.forename: Linda
authors.initials: L
authors.lastname: Koopmans
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Coffeng
authors.affiliation: Body@Work, Research Center for Physical Activity, Work and Health, TNO-VU University Medical Center, Amsterdam, The Netherlands. claire.bernaards@tno.nl.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Bernaards
authors.forename: Cécile R L
authors.initials: CR
authors.lastname: Boot
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Hildebrandt
authors.forename: Henrica C W
authors.initials: HC
authors.lastname: de Vet
authors.forename: Allard J
authors.initials: AJ
authors.lastname: van der Beek
mesh_terms: D000328:Adult; D004650:Employee Performance Appraisal / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D009426:Netherlands; D009786:Occupational Health Services; D016032:Randomized Controlled Trials as Topic; D012063:Relaxation; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D017132:Workplace