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	Supports Intensity Scale	Model Disability Survey
Field	Disability Studies	Disability Studies
Family	Latent structure	Process / pipeline
Year of origin	2009	2022
Originator	James R. Thompson and the American Association on Intellectual and Developmental Disabilities (AAIDD)	World Health Organization and World Bank (Model Disability Survey collaboration)
Type	Standardized support-needs assessment scale	General-population survey operationalizing the ICF biopsychosocial model of functioning
Seminal source	Thompson, J. R., Bradley, V. J., Buntinx, W. H. E., et al. (2009). Conceptualizing supports and the support needs of people with intellectual disability. Intellectual and Developmental Disabilities, 47(2), 135-146.	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	SIS, AAIDD Supports Intensity Scale, Support Needs Assessment, Supports Intensity Level Scale	MDS, WHO Model Disability Survey, Metric Disability Continuum Survey, ICF-Based Functioning Survey
Related	3	3
Summary	The Supports Intensity Scale (SIS) is a standardized assessment developed by the American Association on Intellectual and Developmental Disabilities (AAIDD) to measure the pattern and intensity of the supports a person with intellectual or developmental disability needs to participate in everyday life. Rather than cataloguing deficits or measuring impairment, the SIS reframes assessment around the supports paradigm articulated by Thompson and colleagues, asking what kinds and amounts of help a person requires to take part in valued activities. It surveys support needs across six life-activity domains — home living, community living, lifelong learning, employment, health and safety, and social activities — together with protection and advocacy and exceptional medical and behavioral needs. Each relevant activity is rated on three independent dimensions: how often support is needed, how much daily support time it consumes, and what type of support is required. These item ratings are converted into standardized subscale scores and an overall Supports Intensity Index that supports person-centered planning and the equitable allocation of resources.	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.