Health >> Disability >> Disability: Notes & Sources

Disability: Notes & Sources


Activity limitations: 

  • Activities include walking, hearing, using a telephone, or working at a job. 
  • A person who can walk but cannot walk three city blocks has a mobility limitation.
  • Assistive devices may remove activity limitations without eliminating the impairment: a person who cannot walk may be able to move around easily in a wheelchair.
  • Environmental modifications can also reduce activity limitation. For example, sidewalks, curb cuts, and ramps enable wheelchair users to travel in environments that would not otherwise be accessible to them.

Americans with Disabilities Act (ADA):  This federal civil rights legislation, initially passed in 1990 and amended in 2008, prohibits discrimination on the basis of disability. The law created a need for measures that could both assess the scope and magnitude of specific activity limitations and track whether people with such limitations were adequately accommodated.  In response to this need, the U.S. Census Bureau modified its questions on disability to focus on 6 common types of limitations that were likely to require accommodation under the ADA. 

The Census Bureau tracks limitations in hearing, vision, ambulation, cognition, independent living, and self care.  These 6 specific activity limitations are a subset of all reported disability. Hence, Census rates of activity limitation are lower than disability rates from the Behavioral Risk Factor Surveillance Survey (BRFSS).   Many factors beyond the Census activity limitations can limit a person’s normal activities and result in disability. The Census measures do not distinguish among the underlying impairments that produce a limitation. Persons who are limited in ability to walk or climb stairs are all classified as having an ‘ambulatory limitation’, whether due to a hereditary condition, an injury, or a chronic disease such as arthritis.  The strength of the Census activity limitation measures is in their specificity and in the availability of the data for areas as small as 20,000 people.

Disability is in many ways a relative concept, reflecting a complex interaction between a person’s capacities and the demands of her/his environment. The term generally refers to a restriction in ability to perform the major activities of life because of a physical, mental, or emotional impairment or condition.

  • Impairment refers to an abnormality or loss, either of a body part or of a function.
  • Impairments can be physical (e.g., cancer or loss of a limb), functional (e.g., loss of sight), emotional (e.g., schizophrenia or depression), or cognitive (e.g., dementia).
  • An impairment may be due to a health condition or chronic disease, but having an impairment does not necessarily mean an individual is sick or in poor health.

Employment status:  “Not in workforce” refers to adults who were unable to work, retired, unemployed, homemakers, or students.

Federal Poverty Guidelines are issued by the Department of Health and Human Services and are used to determine financial eligibility for various federal, state, and local assistance programs. The guidelines are based on the Census Department’s federal poverty thresholds. For a family of 4, the federal poverty guideline was $22,050 in 2010; in 2013 it was $23,550.

The Federal Poverty Threshold was adopted in 1964 as an “absolute measure” by which progress in the War on Poverty could be assessed. It is updated annually by the Census Bureau, and is used to calculate official population statistics on the number of Americans in poverty. Its usefulness has diminished over the past half century, as it almost certainly underestimates poverty in the United States. Specific shortcomings include:

  • Lack of adjustment for regional costs
  • Calculation based totally on the cost of food, ignoring significant contributions from housing, transportation, utilities, health care, and child care
  • Reliance on pre-tax earnings, excluding the effects of tax adjustments, food stamps, housing benefits, and other transfers.

Measures of disability typically record limitations in activities. Communities Count reports disability data from 2 different surveys. Each survey provides a different perspective on disability.

  • A broader, more general perspective comes from the annual Behavioral Risk Factor Surveillance Survey (BRFSS), a population survey of adults by the Washington State Department of Health. In this survey, a person who reports being limited in any way by a physical, emotional, or mental problem, or having a health problem that requires use of equipment such as a cane, wheelchair, special bed, or special telephone is counted as having a disability.  This definition was developed by the US Centers for Disease Control and Prevention (CDC) to include adults with a wide range of impairments and limitations.
  • A narrower focus on specific activity limitations is provided by the US Census Bureau. The annual American Community Survey (ACS) poses 6 questions about limitations in hearing, vision, ambulation, cognition, independent living, and self-care.  These more precise questions yield data that help monitor the need for specific disability accommodations, as mandated in the Americans with Disabilities Act of 1990.

Confidence interval (also called "error bar") is the range of values that includes the true value 95% of the time. If the confidence intervals of two groups do not overlap, the difference between groups is statistically significant (meaning that chance or random variation is unlikely to explain the difference).

King County regions: The geographic boundaries of the four King County sub-regions (North, Seattle, East, and South) are defined by the aggregation of ZIP codes adults for adults and by the aggregation of school districts for teens.

Race/Ethnicity: Federal standards mandate that race and ethnicity (Hispanic origin) are distinct concepts requiring 2 separate questions when collecting data from an individual. "Hispanic origin" is meant to capture the heritage, nationality group, lineage, or country of birth of an individual (or his/her parents) before arriving in the United States. Persons of Hispanic ethnicity can be of any race. Communities Count's terms for racial/ethnic groups are derived from those used by the U.S Census Bureau in 2010.

  • Communities Count terms:  Hispanic, Non-Hispanic, White Non-Hispanic, Black, American Indian/Alaska Native (AIAN), Asian, Native Hawaiian/Pacific Islander (NHPI), White, and Multiple Race (Multiple). Persons of Hispanic ethnicity can be of any race and are included in other racial categories. Racial/ethnic groups are sometimes combined when sample sizes are too small for valid statistical comparisons of more discrete groups. 
  • 2010 Census terms: Hispanic or Latino, Not Hispanic or Latino, White alone (Not Hispanic or Latino),  Black or African American, American Indian or Alaska Native, Asian, Native Hawaiian or Other Pacific Islander, White, Some Other Race, and Two or More Races.


Age effects:  To examine the possibility that age differences might explain some of the significant relationships between disability and race/ethnicity, gender, income, education, employment,  relationship status, children in household, military service, sexual orientation, and health, separate analyses were run excluding adults of different age groups (65 and older, 45 and older, 30 and older).  Where relevant, the results of these age-specific analyses are reported in the narrative. 

Data have been averaged over 3 or 5 years to enable comparisons across groups that would otherwise be too small for detection of statistically significant results.

Data table for specific activity limitations:

Sexual orientation and disability: Although causal connections have not been proven, data from multiple sources have converged on findings of higher health risk profiles for LGBT adults (e.g. higher rates of overweight among women and smoking in men and women; lower rates of preventive screenings among women). These are presumed, but not proven to result in higher disability rates. 

Statistical significance: Unless otherwise noted, any difference mentioned in the text is statistically significant (unlikely to have occurred by chance).

Data Sources

Data on broad disability rates (“any limitation”) come from the Washington State and national Behavioral Risk Factor Surveillance System (BRFSS). The BRFSS is a random telephone interview survey of non-institutionalized adults ages 18 and older that has been conducted in King County every year since 1987. Starting in 2003, the BRFSS was administered in English and Spanish. The limitations of an English-and-Spanish-only telephone survey include the following: a) people who do not have a land line telephone or who do not speak English or Spanish are excluded, and b) people who have less education and lower incomes are underrepresented.  Respondents who answer “yes” to either of the questions below are classified as having a disability:
  • Are you limited in any way in any activities because of physical, mental, or emotional problems?
  • Do you now have any health problem that requires you to use special equipment, such as a cane, a wheelchair, a special bed, or a special telephone?  (The response includes occasional use or use in certain circumstances.)

Data on specific activity limitations come from the US Census Bureau’s American Community Survey (ACS,  The ACS classifies a person as having a disability if the person (or a proxy respondent) answers “yes” to any of the questions below:

  • Is this person deaf or does he/she have serious difficulty hearing?
  • Is this person blind or does he/she have serious difficulty seeing, even when wearing glasses?
  • Because of a physical, mental or emotional condition does this person have serious difficulty concentrating, remembering, or making decisions?
  • Does this person have serious difficulty walking or climbing stairs?
  • Does this person have difficulty dressing or bathing?
  • Because of a physical, mental, or emotional condition does this person have difficulty doing errands alone such as visiting a doctor’s office or shopping?

To find specific data tables for ACS data presented here, listed below, go to  and search for the tables listed below:

  • Prevalence of one or more activity limitations by age & gender, population age 5 and older (ACS Table B18101,2009-2011)
  • Number of persons with each type of activity limitation by age (ACS 2009-11, Table S18121, adjusting  the ACS numbers to the 2010 Census population by age group from Table QT-P1).
  • Education level, adults age 25+ by activity limitation (Table S1811, 2009-11 ACS)
  • Employment (fulltime/part time) by type of activity limitation, adults 18-64 (Table B18121, 2009-11 ACS)
  • Poverty by activity limitation & labor force status, adults 20-64 (Table B23024, 2009-2011 ACS)

Other Sources

Background and definitions of disability and specific activity limitations:

City Health Profiles provide demographic and health information for 25 geographic areas in King County – mostly large cities (e.g., Seattle, Bellevue), groups of small cities (Bothell/Woodinville), or combinations of cities with nearby unincorporated areas (e.g., Renton/Fairwood). Each report has seven sections:
  • Demographics
  • General health status
  • Leading causes of death
  • Health risk factors and chronic diseases
  • Injury and violence-related mortality
  • Maternal and infant health
  • Access to care and preventive services
Maps of King County covering a wide range of topics can be accessed at  Maps most immediately relevant to Communities Count are under the headings of Community data & demographics, Public health, and Environment & natural resources, but other maps should be useful as well (farmers markets, transit routes, walking and biking routes, parks, traffic counts, etc.).

Specific comparisons of BRFSS and ACS disability definitions and data: