Factor structure and longitudinal measurement invariance of the demand control support model: an evidence from the Swedish Longitudinal Occupational Survey of Health (SLOSH).
OBJECTIVE
To examine the factor structure and to evaluate the longitudinal measurement invariance of the demand-control-support questionnaire (DCSQ), using the Swedish Longitudinal Occupational Survey of Health (SLOSH).


METHODS
A confirmatory factor analysis (CFA) and multi-group confirmatory factor analysis (MGCFA) models within the framework of structural equation modeling (SEM) have been used to examine the factor structure and invariance across time.


RESULTS
Four factors: psychological demand, skill discretion, decision authority and social support, were confirmed by CFA at baseline, with the best fit obtained by removing the item repetitive work of skill discretion. A measurement error correlation (0.42) between work fast and work intensively for psychological demands was also detected. Acceptable composite reliability measures were obtained except for skill discretion (0.68). The invariance of the same factor structure was established, but caution in comparing mean levels of factors over time is warranted as lack of intercept invariance was evident. However, partial intercept invariance was established for work intensively.


CONCLUSIONS
Our findings indicate that skill discretion and decision authority represent two distinct constructs in the retained model. However removing the item repetitive work along with either work fast or work intensively would improve model fit. Care should also be taken while making comparisons in the constructs across time. Further research should investigate invariance across occupations or socio-economic classes.
Stress Research Institute, Stockholm University, Stockholm, Sweden. holendrosingh@gmail.com
Holendro Singh
HS
Chungkham
Michael
M
Ingre
Robert
R
Karasek
Hugo
H
Westerlund
Töres
T
Theorell
D005163:Factor Analysis, Statistical; D006306:Health Surveys; D006801:Humans; D008137:Longitudinal Studies; D008962:Models, Theoretical; D016272:Occupational Health / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D013548:Sweden