Notes from "Counting Working-Age People with Disabilities"

Book Discussed

Houtenville, A. J., Stapleton, D. C., Weathers, R. R. II, & Burkhauser, R. V. (Eds.). (2009). Counting working-age people with disabilities: What current data tell us and options for improvement.  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

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I read several chapters of this inexpensive book.  This post presents my notes on (as distinct from a review of) those chapters.

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Preface

I had previously noticed that Cornell had a website with a lot of information on disability statistics.  This preface explains why.  The U.S. Department of Education’s National Institute for Disability and Rehabilitation Research (NIDRR) awarded Cornell a grant for a Rehabilitation, Research, and Training Center (RRTC) (which Cornell called StatsRRTC).This book grew out of a conference on disability statistics research in Washington, DC in October 2006.

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Chapter 1

Stapleton, D. C., Houtenville, A. J., Weathers, R. R. II, & Burkhauser, R. V. (2009). Purpose, overview, and key conclusions.  In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 1-26).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

The title's focus on working-age people follows from an earlier article by Weathers in which he identified the 18-64 age group as being the traditional group of working age, and further pared away the 18-24 group as being in a school-to-work transition stage, and the 62-64 group as being in a work-to-retirement transition stage.  As in that earlier article, this chapter (p. 6) focuses on the group of people aged 25-61.

The authors identify (p. 9) a number of reasons why state-level data on the prevalence of people with disabilities (PWDs) are important -- why, that is, federal data do not capture important local variations.  Some of the reasons include different physical, cultural, economic, and policy environments.  They refer (p. 13) to the National Disability Data System (NDDS), which does not exist in any formal sense (although it should) but can be understood, at present, as the aggregate of a number of disparate data collection and analysis efforts on federal and other levels.  For instance, data from administrative records suggest that only about half of the total number of PWDs estimated by the American Community Survey (ACS) are actually enrolled in federal programs that provide assistance to PWDs (p. 15).

One section of this chapter discusses shortcomings in statistical knowledge about disabilities.  The book has whole chapters that address this and related topics, so I did not read this section in any detail.  I was surprised, though, to see the authors praise the 2008 ACS as having “an improved set of disability questions” (p. 23).  I had not thought that the new set of questions was better, but of course I was not the expert.  So while I was not sure, at this point, that I would read those chapters in their entirety, I was interested to see what this book said about the new ACS.

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Chapter 2

Weathers, R. R., II (2009). The disability data landscape. In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 27-68).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

Weathers says that this book will be using concepts based on the International Classification of Functioning, Disability and Health (ICF) published by the World Health Organization (WHO).  The concepts from the ICF are “impairment,” “activity limitation,” “participation restriction,” and “disability.”  An impairment is “a significant deviation or loss in body function or structure” (p. 29).  An activity limitation is “a difficulty that an individual may have in executing activities,” particularly activities of daily living (ADLs) (i.e., activities inside the home, e.g., dressing).  A participation restriction is “an inability to engage in societal activities”; it can be either a work limitation or an instrumental activity of daily living (IADL) (i.e., an activity outside the home, e.g., shopping).  A disability is any one or more of these (e.g., an impairment that is also an activity limitation).  Weathers further divides impairments into sensory (e.g., hearing, seeing), physical (i.e., difficulty performing physical functions), and mental (i.e., difficulty performing mental functions).

Weathers uses these distinctions to talk about what one can learn from five major surveys:  the American Community Survey (ACS); the Community Population Survey (CPS), and especially its Annual Social and EConomic supplement (CPS-ASEC); the 2000 Decennial Census; the National Health Interview Survey (NHIS); and the Survey of Income and Program Participation (SIPP).  Weathers notes that “the disability data landscape is rapidly evolving” (p. 61); for example, he says new disability-related questions are being added to the CPS and to the Behavioral Risk Factor Surveillance System (BRFSS) produced by the Centers for Disease Control (CDC).  There have also been other changes since Weathers wrote this chapter (apparently around 2006), including the elimination of disability questions from the Census (which I therefore don’t discuss here) and the revision of disability questions in the ACS.

In an analysis that may not be entirely current, Weathers traces how each of these surveys operationalizes these concepts.  In the case of mental impairments, for example, the ACS asks about difficulty in learning, remembering, or concentrating because of a physical, mental, or emotional condition lasting at least six months; the CPS-ASEC has no questions; the NHIS asks about sadness, nervousness, worthlessness, etc. over the past 30 days; and the SIPP asks if you have a learning disability, mental retardation, a developmental disability, a problem with confusion or forgetfulness, or any other mental or emotional condition.

Weathers identifies four main kinds of questions that these surveys can be used to answer:  distinguishing subpopulations (e.g., the NHIS and the SIPP ask numerous questions, so you can tell what’s happening with with people who have severe vision disabilities, whereas the ACS doesn’t distinguish different types of impairments (see preceding paragraph)); capturing state and local disability data (only the ACS); capturing long-term trends (especially the CPS and the NHIS); and capturing changes in the circumstances of the same individuals through reinterviewing (especially the SIPP, also the CPS).  The message from this analysis is that the best results come from knowing what each tool can do and being able to use them in combination when necessary.

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Chapter 3

Houtenville, A. J., Potamites, E., Erickson, W. A., & Ruiz-Quintanilla, S. A. (2009). Disability prevalence and demographics. In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 69-100).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

The authors say that there is a “generally accepted conclusion that there has been a decline in disability among the elderly,” and there seems to have been no change for the working-age population (aged 25-61) from 1997 to 2000, but there was a sharp rise for the working-age population between 1984 and 1996 (pp. 72-73).  The total increase during that period varied by age group:  18%, for those aged 18-29; 52%, for those 30-39; 46%, for 40-49; and 20%, for 50-59.  This change is theorized to stem from either a change in health or an increase in reporting.

In 2006, working-age disability prevalence by state varied from 9.1% in New Jersey to 21.4% in West Virginia, with a median of 12.6%.  There were fairly strong regional tendencies.  All southern states from New Mexico to West Virginia (except Texas, Georgia, Florida, and Virginia) were in the worst bracket; no other states except Alaska, Maine, and Montana were in that bracket.  The second-worst group was dominated by the other states of the Northwest, from Wyoming westward, and by the midwestern states from Missouri to Pennsylvania (including Michigan, excluding Illinois).  The best rates were California-Nevada, Colorado, the north-central states (including Illinois, excluding North Dakota), and the small states (except Rhode Island and Delaware) from Massachusetts to Maryland.

Working-age disability rates in 2006 varied dramatically by age and race.  All categories of disability (e.g., physical, mental) appeared at least two to three times more frequently among people in the 55-61 group as in those aged 25-34.  Only 6% of Asian-Americans, but 22% of African Americans, reported any disability.

The authors note that differences in socioeconomic status (SES) may explain some of these variations among states and races.  SES can influence lifestyle factors (e.g., smoking, obesity), access to health care, and the kinds of jobs that people have.

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Chapters 4-7:  not covered here

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Chapter 8

Ballou, J., & Markesich, J. (2009). Survey data collection methods. In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 265-298).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

Here is the chapter's summary (pp. 290-291):

Recommended Best Practices

Include people with disabilities

PAR [participatory action research] must be considered. Although there is limited research to document the differences in research conducted with and without the participation of people with disabilities, current evidence suggests data quality can be improved by including people with disabilities. Researchers should be vigilant about addressing the need to include people with disabilities in all phases of the survey process.

Use available resources

Surveying Persons with Disabilities: A Source Guide (Markesich, Cashion, and Bleeker 2006) provides a starting point for any disability research project. Although the research included in the collection of sources may not be definitive, these citations provide extensive information related to the methodological issues associated with surveying persons with disabilities and include documentation on approaches that have been used to improve accessibility.

Plan your research

Using the guidelines listed in Table 8.2, researchers must keep in mind the key steps in the process that can impact data quality, particularly for research about and with people who have disabilities. At a minimum, reviewing these guidelines can help in making thoughtful and deliberate decisions about survey methods. In addition, information in this chapter identifies steps in the survey process where particular attention is needed to improve measurement quality.

Train interviewers

Current research identifies what interviewers should know to make sure they have the tools needed to communicate with people who have disabilities. This training should include recognition of types of disabilities, criteria for the selection of proxies, and options that can be used when interviewing people with disabilities, such as alternate wording of questions and qualitative approaches that may differ from interviews with people who do not have disabilities.

Provide documentation

The information presented in Table 8.1 shows what is needed to provide full disclosure of survey methods. It is feasible to provide complete and easily accessible documentation on disability survey information, and doing so has the added benefit of describing how various methods improve survey quality. This documentation is also essential for analysis to assist researchers in evaluating data quality.

Perfecting Best Practices

Meta-analysis of current research

A useful next step would be to conduct a meta-analysis that synthesizes data on similar topics. A systematic analysis of information would identify consistent research results that can be used to set best practice standards with increased confidence and to target the knowledge gaps that require research.

Conduct methodological and experimental research

We described examples of research that is needed to inform a set of best practices for surveying persons with disabilities in our discussion of the steps in the survey process: sampling, questionnaire design, and data collection methods. A goal of the planning group was to establish priorities for future research. This was a tremendous challenge because there are multiple issues that need to be addressed. Information from a meta-analysis could provide guidance on future research priorities.

Educating researchers, both those using data for analysis and those designing surveys to obtain data from and about people with disabilities, will result in improved disability information. One of the major changes needed in disability research is the inclusion of people with disabilities in all phases of the process. Being attentive to the methods used to collect survey information will increase the confidence that the data used for a range of public policy and service provision decisions more accurately represents people with disabilities.

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Chapter 9

Stapleton, D. C., Wittenburg, D. C., & Thornton, C. (2009). Program participants. In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 299-352).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

This chapter discusses programs that provide data about “working-age (aged 18-64) participants in the largest federal and federal-state programs that serve people with disabilities, including Social Security Disability Insurance (SSDI), Supplemental Security Income (SSI), Medicare, Medicaid, state vocational rehabilitation (VR) services, and disabled veterans benefits programs” (p. 299).  These are sometimes called “administrative” data sources, as distinct from “survey” data sources.

The authors are particularly interested in efforts to “match” administrative and survey data sources.  Generally, this appears to mean that survey participants agree to give researchers access to their personal files maintained in administrative databases.  Matching expands the amount of information that survey researchers can draw upon to understand groups of participants.  Given the sensitive nature of confidential medical and other administrative records, there are several major restrictions upon researchers’ access to such data.  The Census Bureau has come up with an alternative, known as a “synthetic” data file, in which the individual data points do not correspond with any actual human being, but collectively the data represent the characteristics of the target population.

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Chapter 10

She, P., & Stapleton, D. C. (2009). The group quarters population.  In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 353-380).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

There is the household population, and then there is the nonhousehold population.  The latter includes people who live in institutional group quarters (GQ), noninstitutional GQ, and homeless settings.  The ACS is in the process of becoming the main source of information on disabilities among the nonhousehold population.  That population is believed to have disabilities at far higher rates than the household population. 

The authors use the 2000 Census and three surveys of prison and jail inmates:  the Survey of Inmates of Local Jails (SILJ), the Survey of Inmates of State Correctional Facilities (SISCF), and the Survey of Inmates of Federal Correctional Facilities (SIFCF).  The authors welcome the recent expansion of the ACS to include the GQ population, but note that it “does not contain the wealth of information that can be found in other surveys of the household population” (p. 374).

In the institutional GQ, the authors observe that, up through 2000, there was a gradual decline in the percentage of the general population that lives in nursing homes, and a rapid rise in the share of the population that consists of people (especially young men) in correctional facilities.  The latter phenomenon seems posed to halt if not reverse, given current budget difficulties in many governmental entities. Nonetheless, the draining of people with (especially mental) disabilities from the household population into the nonhousehold population, especially into correctional facilities, may artificially depress the reported rate of disabilities in the household population:  “It is possible that growth in the incarceration of young adult males helps to substantially explain the decline in disability prevalence for young males” (p. 372).

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Chapter 11

Stapleton, D. C., Livermore, G. A., & She, P. (2009). Options for improving disability data collection. In A. J. Houtenville, D. C. Stapleton, R. R. Weathers, II, & R. V. Burkhauser (Eds.), Counting working-age people with disabilities: What current data tell us and options for improvement (pp. 381-418).  Kalamazoo:  W. E. Upjohn Institute for Employment Research.

The differences in time horizons and other features of the major surveys (see the last paragraph under Chapter 2, above) means that they can complement one another if they are asking the same questions.  To this end, the ACS questions are now used also by the CPS and NHIS.  But there is generally a tradeoff between large sample sizes (as in the ACS, which covers large numbers of people and therefore can provide estimates down to the county level) and the amount of information collected per person.  That is, the ACS questions do not capture the same amount of detail as some of the others (e.g., SIPP):  “One particular concern is that the ACS might fail to identify many people with significant psychiatric conditions” (p. 391).  Moreover, there are typically not enough people with a particular health condition to provide much detail from a statistical perspective.

According to the authors, “The surveys that provide the most in-depth information about people with disabilities are those that are conducted very infrequently or have only been conducted once” (p. 387).  In particular, “The NHIS Disability Supplement (NHIS-D) represents the most ambitious effort to date to collect a wide range of disability-relevant information from a large, nationally representative sample of people with disabilities of all ages.  The survey was conducted in two phases in 1994 and 1995.  The data are now more than a decade old, and the survey has not been repeated” (p. 388).

The authors advocate including the ACS questions in all federal surveys:  “In 1977, the [Office of Management and Budget] mandated the use of a standardized set of questions on race and ethnicity in all federal data collection.  A similar mandate for those at risk for disability now seems justified and would be welcomed by many users of disability data and statistics” (p. 392).  The reason is to provide comparability among surveys.  If, for example, the SIPP included the ACS questions, both would show the same prevalence of disabilities, but the ACS would then be supplemented with the greater data and somewhat longitudinal advantages of the SIPP.  That is, researchers would have much more insight into the characteristics of that 10% or 12% of the population that is identified as having a disability.  Presumably it would also be possible to speculate, at least, about county-level disability details (e.g., the numbers of people having a certain disability in a certain county) by interpreting SIPP data in light of ACS county-level data.

The authors advocate a number of other improvements to disability data collection, including stronger longitudinal data collection (especially in the SIPP), better matching of administrative and survey data, and better researcher access to matched records.  The authors want to see periodic disability supplements to existing surveys, periodic surveys of specific subpopulations, and periodic national disability surveys like the NHIS-D.  The top priorities, they say, are the inclusion of ACS questions in all federal surveys and the strengthening of longitudinal and administrative data (p. 410).

American Community Survey: 2008 Update: Defining Disability

In previous posts, I have looked into the prevalence of disabilities in the United States, as measured especially by the American Community Survey (ACS), especially in 2003. This post takes a first step toward updating the ACS measurement of disabilities, in light of changes made between 2003 and 2008.  The focus here is on the definition of disability under the 2008 ACS.

As of 2008, the ACS 2008 Subject Definitions (p. 38) defined disability as “the restriction in participation that results from a lack of fit between the individual’s functional limitations and the characteristics of the physical and social environment.” The Census Bureau asserts that “disability is not seen as intrinsic to the individual”; nonetheless, the Bureau also identifies “four basic areas of functioning” in which respondents might have “serious difficulty.” In that sense, the language still seems to reflect an impression that disabilities are the individual’s problem, rather than a mutual “lack of fit.” For instance, one might expect a different outcome if respondents were presented with a broader inquiry into functional limitations perceived either by themselves or by others in their lives (e.g., employers, neighbors, family members).

In what the Subject Definitions (p. 38) describe as “a conceptual and empirical break from earlier years,” the 2008 ACS still had six questions about disabilities, but now sought to identify “serious difficulty in four basic areas of functioning: vision, hearing, ambulation, and cognition,” and also included “two questions to identify people with difficulties that might impact their ability to live independently.”

These changes followed from a 2006 American Community Survey Content Test, whose results in the area of disability were written up by Brault and Stern (2007) in an Evaluation Report Covering Disability. The 2006 Content Test was driven by a concern with improved reliability in survey results (Brault & Stern, p. 9), not by a concern with capturing the full numbers of people with disabilities. To the contrary, Brault & Stern admit that some of the changes in the ACS disability questions tend to reduce reported prevalence (p. 8) and that the 2006 Content Test used data collection modes that contained “inherent barriers to collecting disability data” (p. 15). The latter point is important because the regular ACS appears to use essentially the same methods.

In a separate report attached as Appendix B to the Brault and Stern (2007) report (above) (i.e., beginning at page 33 of that PDF), Miller and DeMaio (2006) indicated that, for purposes of consistency with the Americans with Disabilities Act (ADA), an unspecified ACS subcommittee determined that disability would be defined as “a mental or physical impairment that substantially limits at least one major life activity” (p. B-2).  That subcommittee appears to have approached that question by exploring “domains of limitation” or “limitation domains” (pp. B-2, B-3), instead of taking the seemingly obvious step of deciding what counts as a major life activity.

To cite some rather choice examples, Miller and DeMaio did not indicate that the subcommittee considered sleep, sex, or socializing to be major life activities.  All three of those examples seem to involve the Census Bureau’s alleged orientation toward the two-sided question of fit between person and society.  It is society that supplies the people, the stresses, and other key components and determinants of sleep, sex, and socializing.  One would expect, in other words, that these three would be prime candidates for inclusion in the list of major life activities, or as essential contributors thereto.  For instance, there is evidence that sleep deprivation significantly interferes with work and other major daily activities of tens of millions of Americans (Baxter & Kroll-Smith, 2005, p. 39), that it results in substantial numbers of injuries and deaths (e.g., Lyznicki, Doege, Davis, & Williams, 1998), and that one-third of Americans take naps on a typical day (Taylor, 2009).  Although it is presumably not necessary to do so here, one certainly could develop a more extensive argument for sleep, and could make similar arguments for the inclusion of sex, socializing, and other activities that the subcommittee somehow considered not to be "major" for purposes of detecting the existence of a disability.

The subcommittee's decisions in this regard might have been more defensible if the ADA had been construed as taking an interest in major productive activities.  Viewed that way, the subcommittee could reasonably conclude (especially in a traditional industrial economy) that it is all right if workers are tired, as long as they keep working.  Likewise, if industrial-type productivity were the stated focus, attention to sex and socializing would probably seem humorously superfluous.  The full list of impairments that mattered to the subcommittee -- involving vision, hearing, lower body mobility, cognition, activities of daily living (ADLs), instrumental activities of daily living (IADLs), and work (Miller & DeMaio, 2006, p. B-3) would then make sense.  ADLs “generally include self-care type activities such as bathing and dressing,” and IADLs are activities often associated with independent living such as going out alone to shop or visit a doctor’s office” (Brault & Stern, 2007, p. 4), all of which align with an emphasis upon the worker's functionality and his/her ability to remain functional.

Ironically, contrary to the apparent purpose of the ADA, a functional orientation can reinforce stereotyping and exclusionism.  If the majority defines functionality in terms of what the majority can do, then those in the minority will tend to occupy an inferior role.  It will be newsworthy when technology enables them to overcome – say, to run faster than those who began with what was, by definition, a functional advantage (e.g., Christie, 2009).  In reality, there may be many ways (involving e.g., sleep, sex, or socializing) in which many putatively high-functioning people are experiencing profound limitations in major life activities; but that will not be recognized in the ACS until a standard other than industrial-type functionality is used to guide disability determinations.  There would seem to be a number of good, currently relevant candidates for such a standard – ranging from “life, liberty, and the pursuit of happiness” to social capital to adjustment to or satisfaction with life – that could be used alone or in combination for that purpose.

The apparent functional orientation was not the only way in which the 2008 ACS reduced the count of disabilities even below what one might have expected from the subcommittee’s own stated concept. The survey discarded the subcommittee’s broad interest in mental and physical impairments, in favor of very limited kinds of difficulties. The survey’s only questions about mental disabilities were as follows:

18a. Because of a physical, mental, or emotional condition, does this person have serious difficulty concentrating, remembering, or making decisions?

19. 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?

Bizarrely, the 2008 ACS no longer has even the question about work disability (Brault & Stern, 2007, p. 7). That is, there is no question about the presence of a physical, mental, or emotional condition that would limit the kind or amount of work a person can do. So if someone has no problem concentrating etc. (Question 18a), and does not have difficulty doing errands alone (Question 19), it seems s/he would not have a work disability even if s/he spent the workday standing on his/her desk and screaming.

Apparently the question about work disability was deleted because Miller and DeMaio (2006, p. B-32) claimed there was an “excessive extent of misinterpretation and misreporting in this question.” One objection Miller and DeMaio cited had to do with vagueness in the word “work.” Some people reportedly took it to include work around the house. That raised interesting questions in itself, but in any event one version of the test question specified work “at a job or business” (p. B-31). Despite the alleged breadth and complexity of the work construct, Miller and DeMaio devoted only about 1.5 pages to the question of work before recommending its deletion.  (While I did not think that disabilities should be defined exclusively in work-related terms, it did seem obvious that inability to work would be an important indicator of disability.)  That is, Miller and DeMaio did not seriously wrestle with the matter; yet they also did not claim that the question of work-related disability is unimportant.

Bear in mind that Miller and DeMaio (2006), who balked at what they consider excessive vagueness in the work construct, were the same researchers who pointed out that “Respondents’ answers to survey questions are necessarily based on personal experience and perceptions of that experience” (p. B-3), that “it is unfeasible to develop questions that yield a perfect measure of disability” (p. B-4), and that, in connection with a question that was retained in the survey, respondents were being required “to discern a clear line of yes or no in a reality that, for them, was essentially grey and multi-dimensional” (p. B-7). All of these remarks seem to suggest that Miller and DeMaio were generally comfortable with the hard decisions that arise in the process of quantifying experience – including work experience.

Under such circumstances, one might be forgiven for asking whether political considerations during the Bush Administration had any influence upon the choice of researchers and/or the recommendations they made in such regards. In a report on changes to measurement of disability in the 2008 American Community Survey that was produced after Obama’s election, Brault (2009, p. 5) seems to indicate that the previous administration had not prioritized the ACS generally. He says that, “due to budgetary issues, FEFU [i.e., Failed Edit Follow-Up] operations were scaled back from April through September” of 2008.

In his 2009 report, Brault states that the net effect of the changes in questions on the 2008 ACS, including the deletion of the work disability question, resulted in a marked drop in the estimated number of Americans with a disability, from 41.2 million (2007) to 35.9 million (2008). “Given the differences in the questionnaire,” Brault says, “one should not interpret these changes as real differences in the number or percent of people with disabilities” (p. 16).  Brault emphasizes that ACS disability data from 2008 are not comparable with ACS disability data from prior years.

This is not to say that the 2008 ACS is useless for all disability-related purposes. Brault (2008, p. 8) suggests, for example, that the ACS is more likely to capture instances of hearing difficulty than is the Survey for Income and Program Participation (SIPP), because the SIPP excludes hearing difficulties that are corrected by hearing aids. That particular example is not necessarily good or bad in itself, but it does suggest that the ACS may sometimes provide a useful alternate picture on the prevalence of some kinds of disabilities.

There are some other limitations on ACS data.  First, ACS data of all sorts are not yet available for geographic areas with populations of less than 20,000.  In late 2010, according to the Census Bureau, data will be released “for areas as small as census tracts and block groups, nationwide. For very small towns, 2010 will be the first time that ACS data are published. These data products, referred to as 5-year multiyear estimates, will be based on the data accumulated during the 2005-2009 time period.”  The Bureau also says that information on demographic, socioeconomic and housing characteristics will thereafter be available annually for all areas.  These include annual estimates for all areas of 65,000+ population, three-year averages for all areas of 20,000+ population, and five-year averages for census tracts and block groups.  Note also that, starting in 2006, the ACS did begin to include data for the group quarters population.  These data were not available, however, in 15 states that had a total group quarters population of less than 45,000.

Because of the change in the operational definition of disability in the 2008 ACS, the Census Bureau will not be able to provide three-year estimates for disabilities until the 2008-2010 ACS 3-year estimates are released in 2011.  That is, the change in definitions means that users should not compare disability data from 2008 and afterwards to any year before 2008.

Recap So Far

In this series of posts on the prevalence of disabilities in the U.S., I have been moving toward an estimate of disabilities on the local level.  It seemed logical to begin by choosing a national-level survey that would provide local-level data, and then to understand that survey and, on that basis, to interpret its local data.  Preliminarily, the ACS seemed far superior to other federal surveys, in terms of its penetration to the local level.  It did not define disabilities as comprehensively as some other surveys, but it seemed that it might be possible to adjust its reported prevalence rates upwards by some plausible percentage, so as to reach a defensible ballpark figure for actual local disability prevalence.

Unfortunately, this post's critique of the definition of disabilities, and of its operationalization in the 2008 ACS, suggests that the ACS does not provide accurate data on the prevalence of disabilities.  Hence, before conducting further research into federal disability statistics, it presently seems advisable to pursue some other routes.  Several such routes come to mind.  First, there is surely a great deal of relevant third-party literature on the ACS, as distinct from the literature provided by the Census Bureau itself.  Second, there may be good local-level research on the prevalence of disabilities in various types of cities and counties, sufficient to inform an educated guess on prevalence in other similar local areas.  Third, on a more theoretical level, there is no doubt much to learn about the conceptualization of disability -- on, for example, the validity of viewpoints suggested in this post.  Since the conceptualization seemed likely to influence the interpretation of research, my next step in this investigation moved in the conceptual direction.

Definitions of Disability

The Web is filled with references to handicapped people and disabled people and people with disabilities.  But what is a disability?

Iezzoni and Freedman (2008) describe a "medical model of disability" (p. 332) originating in the 19th century. That model, they say, treats disability as a form of illness; and illnesses, in the medical model, are typically diagnosed in individuals and treated by doctors.  Against this, Iezzoni and Freedman contrast the "social model" (p. 333), which considers disability a social phenomenon.  In the words of the Fundamental Principles of Disability (1975) produced by the now apparently defunct Union of the Physical Impaired Against Segregation, "Disability is something imposed on top of our impairments, by the way we are unnecessarily isolated and excluded from full participation in society" (p. 3, cited by Oliver (1996, p. 22)).  In other words, there are a great many physical and mental impairments - the need to wear eyeglasses is an example - but not all impairments are treated equally; some result in much more isolation or stigma than others.

Within the social model of disability, Iezzoni and Freedman (2008) favor the definitional approach adopted by the World Health Organization's (WHO, 2009) International Classification of Functioning, Disability and Health (ICF):

The ICF puts the notions of ‘health’ and ‘disability’ in a new light. It acknowledges that every human being can experience a decrement in health and thereby experience some degree of disability. Disability is not something that only happens to a minority of humanity. The ICF thus ‘mainstreams’ the experience of disability and recognises it as a universal human experience. By shifting the focus from cause to impact it places all health conditions on an equal footing allowing them to be compared using a common metric – the ruler of health and disability. Furthermore ICF takes into account the social aspects of disability and does not see disability only as a 'medical' or 'biological' dysfunction. By including Contextual Factors, in which environmental factors are listed ICF allows to records the impact of the environment on the person's functioning.  [I have notified the webmaster of incoherence in that last sentence.]

Iezzoni and Freedman (2008) note, however, that different definitions serve different purposes, and that at present there are numerous legal definitions in use in the United States.  Two of the most prominent definitions they cite are those of the Americans with Disabilities Act of 1990 (ADA) and the Social Security Administration (SSA).  Section 12102(1) of the ADA defines disability as meaning, with respect to an individual, "(A) a physical or mental impairment that substantially limits one or more major life activities of such individual; (B) a record of such an impairment; or (C) being regarded as having such an impairment."  By contrast, the Social Security Advisory Board (2003) says that the Social Security Act of 1956 defined disability as “inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or to be of long-continued and indefinite duration” (p. 3); but this definition, they say, is increasingly subject to challenge.

The Census Bureau is yet another important source of disability definitions.  Definitions used by the Census Bureau in recent years include the definition of "work disability" in the Current Population Survey; the definition of disability in the Survey of Income and Program Participation; and the definition of disability in the American Community Survey (ACS).  Among these and other data sources that have been used by the Census Bureau, the ACS is especially useful for obtaining local data at the city and county levels.  The 2008 ACS Subject Definitions operationalize the concept of disability in a set of related questions posed to survey participants:

Using models of disability from the Institute of Medicine and the International Classification of Functioning, disability is defined as the restriction in participation that results from a lack of fit between the individual’s functional limitations and the characteristics of the physical and social environment. So while the disability is not seen as intrinsic to the individual, the way to capture it in a survey is to measure components that make up the process. The American Community Survey identifies serious difficulty in four basic areas of functioning: vision, hearing, ambulation, and cognition. Described below, the ACS asks respondents about serious difficulty and the resulting data can be used individually or combined. The ACS also includes two questions to identify people with difficulties that might impact their ability to live independently. In the 2008 American Community Survey, there are three disability questions, two with subparts totaling six questions in all . . . . (p. 38).

These various definitions, including especially that of the ACS, will be relevant to further exploration of data on disabilities within the U.S.