Supports Intensity Scale
Also known as: SIS, AAIDD Supports Intensity Scale, Support Needs Assessment, Supports Intensity Level Scale
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.
Key highlights
- Operationalizes the supports paradigm directly, measuring what help a person needs to participate rather than what they cannot do.
- Separates frequency, daily time, and type of support into independent dimensions, preserving information that single-severity ratings lose.
- Produces norm-referenced subscale scores and an overall index suitable for fair, comparable resource allocation across individuals.
- Feeds naturally into person-centered planning because the profile maps onto the concrete supports services must provide.
Intuition
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How it works
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When to use it
Use the Supports Intensity Scale when you need to assess and plan the practical supports a person with intellectual or developmental disability requires, especially for individualized planning, service design, or the equitable allocation of funding across a population. It is appropriate where the goal is to describe what help a person needs to participate in valued activities rather than to diagnose, classify by impairment, or measure cognitive ability. The SIS works best when respondents who know the person well can be interviewed and when assessment is repeated periodically to track changing needs. It is not a diagnostic instrument and should not be used to establish eligibility based on deficit, nor is it suited to settings where the relevant outcome is achievement, adaptive behavior level, or quality of life itself, which other instruments measure more directly.
Strengths & limitations
- Operationalizes the supports paradigm directly, measuring what help a person needs to participate rather than what they cannot do.
- Separates frequency, daily time, and type of support into independent dimensions, preserving information that single-severity ratings lose.
- Produces norm-referenced subscale scores and an overall index suitable for fair, comparable resource allocation across individuals.
- Feeds naturally into person-centered planning because the profile maps onto the concrete supports services must provide.
- Ratings depend on respondents who know the person well, so the quality of the profile is bounded by informant knowledge and consistency.
- Standardized scores depend on the normative sample, which may not represent every population, age group, or cultural context to which the scale is applied.
- The scale measures support needs, not outcomes or quality of life, so a low index does not guarantee a good life nor a high index a bad one.
- Distinguishing extraordinary support from ordinary, age-typical assistance requires trained interviewers and can introduce rater variability.
Common pitfalls
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Applications
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Frequently asked
How is the SIS different from an IQ or adaptive behavior test?
IQ and adaptive behavior tests measure a person's abilities or functioning, asking what the person can or cannot do. The SIS measures something distinct: the supports a person needs to participate in everyday activities. Two people with similar IQ or adaptive scores can have very different support needs, and the SIS is designed to capture that difference. Thompson and colleagues treat support needs as their own construct, so the SIS complements rather than replaces ability measures and should never be used to diagnose or classify by impairment.
Why does the SIS rate frequency, time, and type separately?
Because these are genuinely different aspects of support that do not move together. An activity might need help only rarely but for a long time when it does, or frequently but only as brief prompting. Collapsing them into a single severity number would discard exactly the information services need to plan. By keeping frequency, daily support time, and type of support independent at the item level and combining them only when computing scores, the SIS preserves a richer picture of what support actually looks like in a person's life.
Can the Supports Intensity Index be used to rank how disabled someone is?
No. The index measures the intensity of support a person needs, not how disabled or capable they are. A higher index means more assistance is required to participate, not that the person is more deficient. Reading it as a severity ranking misrepresents the supports paradigm the scale is built on. The index is intended to help allocate resources and plan supports fairly, and it should always be interpreted alongside the subscale profile, which shows where in life the support need actually concentrates.
Sources
- 1.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.
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Cite this page
ScholarGate. (2026, June 23). Supports Intensity Scale. ScholarGate. https://scholargate.app/disability-studies/supports-intensity-scale