American Community Survey (2003): National Population Statistics

As described in a previous post, I found that the Cornell University Disability Statistics website offered materials that seemed likely to help me estimate the number of people with disabilities (PWDs) in a particular county in the U.S.  The next step was to understand something about the general population terminology and concepts that formed the basis for census calculations.

I had learned that the American Community Survey (ACS) provided the most frequently updated and most recent county-by-county data.  The Guide to Disability Statistics from the American Community Survey (Weathers, 2005, p. 28) indicates that estimates of the numbers of PWDs depend directly upon the number of questions asked. According to Weathers (p. 4), the ACS approach has several limitations:

First, the ACS is limited to six questions that are used to identify the disability
population [as a whole] and it does not allow one to identify the prevalence of specific health conditions (e.g., cancer, paralysis, HIV/AIDS, etc.). Second, the ACS definition does not explicitly include important societal and environmental factors that may contribute to a disability such as discrimination and lack of reasonable accommodations. Finally, the ACS does not capture the population living in “group quarters.” Group quarters include individuals living in institutions, college dormitories, and other types of group quarters. This is a very important limitation in that it may leave out an important segment of the population with disabilities. The Census Bureau plans to address this last limitation of the ACS by including a sample of persons living in group quarters beginning in 2006.

By contrast, at the low end of the scale, according to the Guide to Disability Statistics from the Current Population Survey - Annual Social and Economic Supplement (March CPS) (Burkhauser & Houtenville, 2006, p. 19), the Current Population Survey asks just one question about disabilities -- regarding, specifically, the presence or absence of a work limitation -- and thus "misses a large part of the broader population with disabilities based on an ICF [i.e., International Classification of Functioning] disability conceptualization."  On the other extreme, as Burkhauser & Houtenville (2006, p. 19) also note, the Survey of Income and Program Participation (SIPP) uses 93 disability-related questions.  Generally, they say, "data sets that ask more questions to identify a population with disabilities and that contain a broader disability conceptualization will capture a larger disability population."

Weathers (2005) quantifies the difference made by these varying operationalizations of the concept of disability.  Weathers uses data from 2003.  To analyze these data, it may be helpful to begin by clarifying the meanings of some terms that the Census Bureau uses.

First, the resident population of the U.S. includes all U.S. residents living in the 50 states and the District of Columbia.  That is, it excludes residents of Puerto Rico and American possessions abroad, as well as U.S. citizens living abroad, whether in the military or as expatriates.  This post does not examine the question of whether PWDs may be disproportionately represented in the military -- whether, that is, the percentages of PWDs in their home counties would be noticeably higher (particularly in some age groups and locations) if those members of the Armed Forces were available for inclusion within the count of PWDs under the ACS.

The resident U.S. population as of July 1, 2003 was estimated to be 290,210,914.  According to the 2003 ACS Subject Definitions (p. 13), the resident population is divided into people who live in housing units (i.e., households) and those who live in group quarters.  "Housing units" can include any occupied "unit," including tents and railroad cars; but "If all the people staying in the unit at the time of the interview are staying there for two months or less, the unit is considered to be temporarily occupied, and classified as 'vacant'" (p. 14).  The data include transients (i.e., those who stay only briefly in any one place), however, by including them if there is no place where they usually stay.  Note that "Vacant units are excluded from the housing inventory if they are open to the elements; that is, the roof, walls, windows, and/or doors no longer protect the interior from the elements. Also, excluded are vacant units with a sign that they are condemned or they are to be demolished" (p. 14).  It preliminarily appears, then, that the 2003 ACS data undercount people who are not living in any kind of housing unit but, rather, are living outdoors (e.g., under a bridge) -- among whom, again, there may be a disproportionate number of PWDs.

The Census Bureau indicates that residents of group quarters were sampled in 1999 and 2001, but the 2003 data exclude people living in group quarters.  For purposes of introducing some relevant terms, then, it will be convenient to refer to the 2000 census.  According to the Statistical Abstract of the United States for 2003, table 77 (examining 2000 census data), about 7.8 million people (2.8% of the total resident population of 281,424,602 in 2000) lived in group quarters.  These people were divided almost equally into institutionalized and noninstitutionalized group quarters.  Among the institutionalized individuals in group quarters, by far the largest groups were males aged 18-64 in correctional institutions (44%) and females aged 65+ in nursing homes (29%).  Other institutions include mental hospitals and wards and juvenile facilities.  Among noninstitutionalized individuals in group quarters, 55% were living in college dormitories.  Other noninstitutional group quarters include military quarters, religious group quarters, shelters, and group homes. 

If 2.8% of the total resident population lived in group quarters in 2003, as was the case in 2000 (above), that would mean that just over 8 million (i.e., 2.8% of 290,210,914) lived in group quarters in 2003.  Subtracting those 8 million from the total resident population would produce something like the 282,909,885 people whom the Census Bureau estimated as the total household population in 2003.

The total household population included people of all ages.  In the analysis of disabilities done by Weathers (2005), however, the focus is on people who were between 18 and 64 years of age in 2003.  In the 2003 ACS, to use the slightly adjusted number provided by Weathers, the Census Bureau estimates that there were 176,395,446 people in this age group.  This number is quite close to the 176,305,337 estimated by the SIPP for that year, and roughly midway between the estimates of 172,761,000 from the NHIS and 179,132,544 provided by the CPS.

I will be using the ACS figure in the next step, which addresses the numbers and percentages of people with disabilities within that larger total.  At this point, I join Weathers (2005) in turning from the estimate of the total numbers of people with disabilities in the population, and focus (at least for the time being) upon the prevalence of disabilities among people of traditional working (i.e., post-high school, pre-retirement) age.

Browsing the Cornell University Disability Statistics Website

I wanted to know how many people with disabilities there were in a particular county in the U.S.  I decided to try to answer this on the basis of materials available at Cornell's Disability Statistics webpage.  I hadn't used that webpage previously, but I guessed it would probably have links, at least, to the main sources of data on the numbers of people with disabilities on federal, state, and local levels in the U.S.  In my initial looks at the webpage, I found its layout somewhat confusing.  There also seemed to be quite a bit of material there.  I decided to summarize what I found, for future reference.

The website required me to log in to view its statistics page, so I did.  I wondered where I was, in the grand scheme of things, so I backed out to the main page of the Cornell University School of Industrial and Labor Relations (ILR).  Its research webpage led me to its Digital Commons, which led to its list of research units, which led to its Employment and Disability Institute (EDI), whose collection included a large number of manuscripts from recent years.  This was a bit overwhelming, so I backed up one or two steps and took a slightly different path through the EDI's webpage to its Research page and its Publications page.  The latter looked promising:  it sorted EDI publications into seven areas of expertise, each with its own webpage:  ADA, Accommodation & Accessible IT; Community Inclusion; Disability Benefits and Work; Disability Employment Research; Disability Statistics Research; Educational Achievement & Transition; and International Disability Research.  The Disability Statistics Research link under Publications actually just produced what appeared to be the results of an automatic search.

I went back to the EDI homepage.  This time, I explored the links under the Our Areas of Expertise & Projects heading.  These included ediONLINE; ADA, Accommodation & Accessible IT; Community Inclusion; Disability Benefits and Work; Disability Employment Research; Disability Statistics Research; Educational Achievement & Transition; International Disability Research; and Workforce Development.  Here, the Disability Statistics Research link led, reasonably enough, to the Disability Statistics Research homepage.  It looked like one of those that I had seen before, when I was doing my initial poking around (above).  The main current project shown here was the Rehabilitation Research and Training Center on Disability Demographics and Statistics (StatsRRTC), whose purpose was to bridge the divide between the sources of disability data and the users of disability statistics.  This project's homepage pointed to a list of events, such as a free webinar reviewing a statistics report.  I clicked on one of those events, entitled Discovering Untapped Talent for the Workforce of Tomorrow: Strategies for Employing People with Disabilities.  I was hoping it would lead me to sources of information on the topic, but it appeared to be intended just to notify people of seminars that they would typically have to attend in person.

I backed up a step and tried the Resources page instead of Publications.  This opened up links to the Benequal Organization Assessment webpage; the Disability Medicare Wizard webpage; the Disability Statistics page; the Human Resources (HR) Americans with Disabilities Act Tips page; a Disability Policy Primer; the website of the Longitudinal Study of the Vocational Rehabilitation Services Program; the Northeast ADA [Americans with Disabilities Act] & AIT [Accessible Information Technology] Center; the website for the Plan to Achieve Self-Support (PASS) program; the Person Centered Planning Education Site; the TransQUAL Online website; and the Universal Access New York website.

From those choices, I went into the Disability Statistics page.  I looked through its Statistics and Data Sources pages, but then decided that its FAQs page looked most promising.  There, I gravitated toward its list of Disability Data Source User Guides, with links to the Guide to Disability Statistics from the American Community Survey (ACS) (Weathers, 2005); the Guide to Disability Statistics from the Current Population Survey (CPS) - Annual Social and Economic Supplement (Burkhauser & Houtenville, 2006); the Guide to Disability Statistics from the 2000 Decennial Census (Erickson & Houtenville, 2005); the Guide to Disability Statistics from the National Health Interview Survey (NHIS) Harris, Hendershot, & Stapleton, 2005); the Guide to Disability Statistics from National Health Interview Survey – Disability Supplement (Maag, 2006); the Guide to Disability Statistics from the Panel Study of Income Dynamics (PSID) (Burkhauser, Weathers, & Schroeder, 2006); and the Guide to Disability Statistics from the Survey of Income and Program Participation (SIPP) (Wittenburg & Nelson, 2006).

To choose among those user guides, I looked at the FAQ that indicated which data sources would be most appropriate for various purposes.  That FAQ indicated that the ACS was best for current data on disabilities, but also that data below the state level would be reported only in the 2000 Census.  Looking at Weathers (2005, p. 3), however, I found that the ACS was supposed to provide data at the county and Metropolitan Statistical Area levels as well.  I obtained some additional confirmation of that by going to the Census Bureau's American FactFinder page, using its Get Data link under the ACS heading, and observing that it did offer data from the 2006-2008 American Community Survey 3-Year Estimates.  According to the About This Data Set link for that particular three-year estimate, however, data on disabilities were not included.  Instead, the 2008 American Community Survey 1-Year Estimates provided the most recent data set offering estimates on disabilities.  (One-year estimates were available only for local units of population > 65,000, as distinct from the lower limit of a population > 20,000 applicable to the three-year estimates.)  For actual findings, as distinct from estimates, the most recent survey with data on disabilities was the 2006 American Community Survey, with an accompanying 2006 Quick Guide ("quick" meaning a PDF of only 50 pages).

This look through the Cornell Disability Statistics website suggested that the site provided informative access to a variety of helpful materials, and that the ACS in particular would tend to be the starting point for my work in reaching specific numbers about persons with disabilities in a particular county.  The next step in my inquiry was to try to put some of those materials to use in reaching actual numbers.