Compare methods

	Disability Quality of Life Assessment	Model Disability Survey
Field	Disability Studies	Disability Studies
Family	Latent structure	Process / pipeline
Year of origin	2002	2022
Originator	Robert L. Schalock & Miguel Angel Verdugo; World Health Organization (ICF)	World Health Organization and World Bank (Model Disability Survey collaboration)
Type	Measurement methodology for quality of life in disability populations	General-population survey operationalizing the ICF biopsychosocial model of functioning
Seminal source	Schalock, R. L., & Verdugo, M. A. (2002). Handbook on Quality of Life for Human Service Practitioners. Washington, DC: American Association on Mental Retardation. ISBN: 9780940898776	Sabariego, C., Fellinghauer, C., Lee, L., et al. (2022). Generating comprehensive functioning and disability data worldwide: development process, data analyses strategy and reliability of the WHO and World Bank Model Disability Survey. Archives of Public Health, 80, 6.
Aliases	QOL Measurement in Disability, Health-Related Quality of Life Assessment, Disability HRQOL Methodology, QOL-in-Disability Assessment	MDS, WHO Model Disability Survey, Metric Disability Continuum Survey, ICF-Based Functioning Survey
Related	3	3
Summary	Quality of life assessment in disability populations is the general methodology for measuring how well people with disabilities are living, encompassing both overall quality of life and health-related quality of life. Unlike a single instrument or model, it is a set of methodological commitments and decisions that researchers and practitioners must navigate whenever they attempt such measurement. Drawing on the quality-of-life science consolidated by Schalock and Verdugo and on the biopsychosocial framing of disability in the World Health Organization's International Classification of Functioning, Disability and Health, the methodology distinguishes objective life conditions from subjective evaluation, weighs generic against condition-specific instruments, and confronts phenomena that are especially acute in disability populations. Chief among these are response shift, the tendency for a person's internal standards to change over time, and the disability paradox, in which people with serious impairments often report a good quality of life that observers would not predict. The methodology also insists on accessible administration and valid proxy reporting so that people who communicate differently are measured fairly rather than excluded.	The Model Disability Survey is a general-population survey developed jointly by the World Health Organization and the World Bank to generate comprehensive, internationally comparable data on functioning and disability. Unlike instruments that classify people as disabled or not, it operationalizes the biopsychosocial model of the WHO ICF, treating disability as the outcome of an interaction between a person's intrinsic capacity and the environment in which they live. The survey collects detailed self-reported information on how much difficulty people have across many domains of functioning, distinguishing what a person can do in a standardized environment (capacity) from what they actually do in their own environment (performance), and it separately measures environmental barriers and facilitators. As documented by Sabariego and colleagues in 2022, these responses are combined using a Rasch measurement model into a single metric scale, so that disability is represented as a continuum running across the whole population rather than as a yes/no category. The result is a graded picture of functioning suited to prevalence estimation, equity analysis, and policy on a comparable metric.