Examining the factor structure and hierarchical nature of the quality of life construct.

There is considerable debate in the area of individual quality of life research regarding the factor structure and hierarchical nature of the quality of life construct. Our purpose in this study was to test via structural equation modeling an a priori quality of life model consisting of eight first-order factors and one second-order factor. Data were collected from 769 individuals with mild or moderate intellectual disability from 15 countries in four geographic regions. They all completed a multidimensional quality of life questionnaire. The presence of a single second-order factor in quality of life was empirically demonstrated through confirmatory factor analysis. Comparison of two alternative second-order quality of life factor models was further evaluated. Implications for future research, practice, and public policy regarding services to individuals with intellectual disability are also discussed.