Counting people with disabilities

The signing of the Americans with Disabilities Act on July 26, 1990 represented a major milestone. The law guaranteed equal opportunity for people with disabilities in public accommodations, commercial facilities, employment, transportation, state and local government services and telecommunications.

A common question, however, that still pops up during discussions of disability policy is, “How many people with disabilities are there in the United States?”

Coinciding with the 22^nd anniversary of the ADA, the Census Bureau released a new report – Americans With Disabilities: 2010 – that presented a new look at the prevalence of a wide range of specific disabilities, the degree of severity and the well-being of the population with disabilities.

The report showed the number of people with disabilities increasing over the previous five years to 56.7 million people in 2010 (54.4 million in 2005), while the proportion of the population with a disability remaining unchanged at 18.7 percent of the civilian noninstitutionalized population.

The Americans With Disabilities: 2010 report also shows the prevalence of specific disability types.  For instance, about 8 million adults had difficulty seeing; 9 million adults had difficulty with an activity of daily living (ADL); and 4 million adults had a learning disability. Furthermore, disability is often co-occurring with around 11 million individuals experiencing both physical and mental disabilities.

Measuring disability in surveys, however, is not an easy task and different surveys can generate very different estimates of the size of this population. “With a disability” in one study may not be the same as “with a disability” in another. Depending on the definition used, the context of the questions or methods in which the data are collected, estimates of the size of the population with disabilities have ranged from 22 million (from the American Housing Survey) to 62 million (from the National Health Interview Survey).

The Census Bureau report’s estimate of 56.7 million people with disabilities come from the Survey of Income and Program Participation(SIPP), which uses a comprehensive set of disability questions assessing difficulty on a number of dimensions including communication, physical and mental functions.

Disability statistics from this survey are used by agencies — such as the  Social Security Administration, Centers for Medicare and Medicaid Services and the Administration on Aging — to assist with program planning and management. The SIPP measure has been the primary statistic for estimating the size of the population with disabilities since the early 1990s.

Disability and functioning are continuums ranging from “able to do most or all basic activities with little or no difficulty or help from technology or another person” to “completely unable to do most or all basic activities, even with assistive technology or other aids.” Under this gradient, most people fall somewhere in between. We use categories like “with a disability” and “with no disability” to make it easier to describe the population, even though the threshold for how much difficulty constitutes a disability may not be clear.

Perhaps some of the difficulty in defining disability along this continuum is also found in the issue of choosing which activities should be included in the disability measure.  The American Community Survey (ACS) – a great survey for looking at the social, economic and housing characteristics of subnational geographies like states, counties and metropolitan areas – uses questions on six specific types of disability. With fewer dimensions of disability, the ACS shows a smaller number of people with disabilities (36 million, or 12 percent), but provides statistics at more localized levels.

Researchers, advocates and policymakers should be aware of the reasons for the different estimates of the number of people with disabilities in the U.S.  No one survey estimate is “right” or “wrong” as all surveys must make choices about the type and nature of disability they intend to measure. With the SIPP’s comprehensive set of questions on various disabilities, the Census Bureau (and many across the federal government) have used Americans with Disabilities report estimates, like the current estimate of 56.7 million people with disabilities, and so it is widely accepted as the measure of the size of this population.

By Matthew Brault, Statistician, Health and Disability Statistics Branch, U.S. Census Bureau.