Disability Prevalence -- Where Are We?

This post summarizes the general flow of my posts on disabilities over the past half-year.  I still have a few more posts in draft form, and I'll be wrapping those up shortly, but this is a good point at which to sketch out the picture as it has developed in this blog.

This post originated as an e-mail message to a researcher who seemed potentially interested in looking into data on disabilities.  I wanted to summarize, for him, the questions I have been studying.  As the message grew longer and began to cite my other blog posts, I realized that I should probably just put it up on the blog and refer him to it.  So what was going to be an e-mail message has now become the following paragraphs.

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Let me describe the situation in general terms, and see if there are particular aspects of it that seem to have the best potential for further investigation from a research perspective.  I tend to be somewhat philosophically oriented, so my apologies in advance if it takes me a while to reach the ground.

What the Question Is

The general question is, how many people have disabilities?  There is a definitional aspect to that question.  Speaking strictly from my own perspective, I have posted some blog entries about such matters.  This definitional question matters in the sense that, if we make the circle too small, we deny relevant assistance to people who need it.  An example, in the area of mental disability, is a person who does not qualify for an official psychiatric diagnosis but nonetheless experiences obvious difficulty.

That general question is operationalized in various surveys.  At this level, we move from the purely conceptual to a mix of the hypothetical and the actual.  Elsewhere, I have cited references to a so-called National Disability Data System (NDDS).  The NDDS itself does not exist formally; the concept is that it exists in effect, through the data provided by actual research efforts.   This is still an academic's discussion; at this level we are kicking around various ways of going at the question of disability prevalence.

From there, we move to a more concrete level.  This is the level at which politicians and the public are given specific numbers.  They may not be the right numbers, but that's what footnotes are for.  Most notably, the American Community Survey (ACS) replaces the decennial census; that is, questions about disabilities have disappeared from the latter because the prevalence of disabilities is now being estimated rather than counted.  The ACS is in the process of replacing the census, for this purpose, down to the local level.

Why It Matters

As you can see, I have been trying to get a grasp on what we think we know, and why we think we know it.  But why does it matter?  Why should we care about the prevalence of disabilities?  There seem to be two ways to answer that.

The National Perspective

On one hand, we can approach the issue from a national perspective.  As the posts describe, the disability-related questions on the ACS have been modified, in the last few years, for purposes of improved reliability.  All well and good; but in the process, the estimate of people with disabilities dropped by some 15%.  Meanwhile, more sensitive measures (e.g., the SIPP) have the potential (but, alas, not the financial backing) to show a significantly higher rate.

The nation has a profound interest, budgetary and otherwise, in knowing whether the number of people with disabilities is 38 million or, instead, 53 million (to cite one alternate figure that I have encountered).  A million people here, a million people there, and pretty soon we're talking about real people.  The estimates are definitionally driven, of course, but that's the point:  how much higher does the prevalence rate go if the researcher uses a different, but comparably respectable, definition?

For example:  in an interesting book, Bagenstos contends that the Americans with Disabilities Act (ADA) has been developed in the direction of treating disability as a minority-rights kind of issue.  This, he says, has had the advantage of drawing upon the legacy of civil rights movements of the 1960s and 1970s, thus giving disability rights advocates a certain automatic sense of legitimacy.  The drawback has been that such movements invite opposition from those whom they exclude, particularly if the latter are expected to pay for adjustments to rectify perceived wrongs.

The alternative, Bagenstos says, is to treat the condition in question -- disability, in this case -- as a universal issue, something in which everyone partakes, or is at risk of partaking, through various forms of inability and imperfection.  In this approach, disability prevalence can be calculated without segregating "people with disabilities" into their own conceptual ghetto.  If disability is treated as something that anyone is capable of experiencing, like chickenpox or the flu, but if only a fraction of the population is likely to experience it at any particular point, what is that fraction?

Good question.  But how can we answer it?  The budgetary infeasibility of extending the SIPP to localities across the entire nation, on a par with the ACS, demonstrates that national disability prevalence estimation is presently stuck in a rather absurd place.  Because of its lack of local foundation, it can be gerrymandered, from a desk in D.C., to add or drop five or ten million people here and there, for reasons of statistical or budgetary convenience.  The nation, and the disability community, need something better than that.  The following suggestion illustrates a national alternative on the local level.

The Local Perspective

The relatively narrow operationalization of disability in the ACS is obviously problematic.  If its national estimate of disabilities is on the conservative side, its local estimate will tend to be so as well.

That seems reasonable enough.  But putting it that way highlights a bigger problem.  The idea seems to be that the best way to know whether my neighbor has a disability is to wait for the latest ACS to be completed; wait for the local-level ACS data to be compiled by someone in Washington; adjust that local number upwards by a fudge factor due to the conservative bias of the ACS; and then calculate my neighbor's odds.

Faced with that kind of logic, practical decisionmakers and advocates say, in effect, "Research be damned."  They aren't going to plumb the intricacies of the Supreme Court's latest interpretations of the Americans with Disabilities Act, and they aren't going to invest the time required for a clear understanding of the ACS.  They're going to rely, instead, on what they've heard and what they believe, supplemented by the occasional citation to some source or other.

Suppose we began, instead, from present experience.  Suppose, for example, that I cannot walk to work.  Research on the benefits of outdoor exposure suggests that this state of affairs will tend to make me less happy than I would be if I could walk to work.  The reason for this impairment of my subjective well-being may not be crucial:  it may not matter, for that purpose, whether I can't walk to work because I have no legs or, instead, because the streets between here and there are dangerous for pedestrians.  Either way, I can't do it.

The focus, in that example, is upon achieving a certain outcome.  Outcome-oriented disability estimation is, in essence, the language of actual local life.  The mayor finds that 39% of her constituents are furious about the state of the roads.  They are experiencing some transportation-related disability.  The fact that 3% of constituents are furious about the state of the sidewalks may be politically trivial, but a transportation-related disability nonetheless exists there as well.

Improved accessibility will often be politically infeasible if the public impression is that we are trying to spend a fortune on curb cuts for a small number of people in wheelchairs who never use the sidewalks anyway.  Rather than ask for special handouts, a more defensible view of transportation-related disability would focus on getting the roads and sidewalks into shape for people on foot, in wheelchairs, and in cars.  Infrastructure is essential.  Everyone needs effective transportation.

Summary

Disability has been defined in different ways.  A cursory review suggests that American law is presently oriented toward treating a disability as a flaw in the individual.  Hence, instruments like the ACS look for vision impairments and other personal characteristics that prevent people from functioning like everybody else.  The social model of disability is incorporated only in the limited sense that some survey questions acknowledge, in various ways, that disability may entail mismatch between person and society; yet even that acknowledgement inevitably brings the focus back to the individual.

That approach to disability has the potential to get everyone bogged down in mutual recrimination, with the familiar old vocabularies of "handouts" versus "privilege," and "normal people" versus "the oppressed."  An approach that could be more readily calculated on the local level, and more consistent and politically supportable on the national level, would focus upon desired life outcomes.

Using transportation as a particularly important disability-related outcome, one can ask how many people are not able to get where they need to go within a reasonable amount of time, in a reasonable manner, at reasonable cost.  There are many kinds of transportation-related disabilities in this sense.  Here are some examples:

• People who are disabled from independent transportation because they are under the control of others.  Examples include children and prison inmates.  
• Those whose health precludes independent travel -- hospital inpatients, for instance, and nursing home residents.
• People may also be economically disabled from utilizing independent transportation:  for instance, they may not have money for a car or even for bus fare, assuming there is a bus line near them.
• People whose obligations prevent independent travel:  people have to stay at work, or have to stay near a certain location to be available for work, or have to stay home with the kids or with a sick relative.
• Social disability precluding independent transportation.  People are stared at and harassed if they are someplace where, in effect, they don't belong.  This can include kids in the vicinity of a bully, women who are out late alone, bicyclists on a busy street, individuals of an unfamiliar or unwelcome race, and people who dress funny or act funny.

The purpose of such an investigation would be to provide an alternative perspective that would be more immediately familiar to the public and more responsive to actual human experiences of disability.  The idea is that, for whatever reason, some people can't get where they need to go.

Needless to say, this post does not purport to address the gamut of disability-related concerns and issues.  Indeed, it is precisely not that sort of thing.  What I have observed, in my half-year of exposure to disability-related matters, is that the cerebral model of disability -- the one that begins with abstract, individual-oriented definitions and works its way down to concrete application -- is not really very practical.

It tentatively seems that it would be more useful, marketable, and appropriate to treat disability as a matter of sociopersonal constraints that everyone experiences in various forms, and to focus especially upon those global, national, state, and/or local conditions that most profoundly impair the achievement of the most important outcomes.  This approach would still prioritize many individual impairments, but would do so as a matter of an investment in society's future rather than as a handout to a person who has managed to become privileged in the eyes of the law.

Cornell's EDI 2008 Disability Status Report Webinar: A Review

Today, I watched a webinar presented by the Employment and Disability Institute (EDI) within the ILR School (formerly the School of Industrial and Labor Relations) at Cornell University.  Elsewhere, I have outlined some of the materials available on EDI's website generally.  Among those materials, it may be worth noting that EDI occasionally offers other webinars.  EDI maintains a Current News Bulletin webpage (also available in PDF and via RSS feed) that provides notifications of those webinars as well as notices of other disability-related developments; that webpage (or PDF or RSS) appears to be the best way of keeping up with such events. (The news bulletin appears to be produced by the DBTAC for the northeastern region (as distinct from the New England region), which in turn appears to be hosted by ILR.)

Today's webinar was described as "DisabilityStatistics.org Presents: The 2008 Disability Status Report."  The slides used in this webinar are presently available for PDF download.  As those slides indicate, the webinar amounted to a simple presentation of information that already seems to appear in EDI's Disability Status Reports.  It was, in other words, a video of a series of slides with voice-overs.


No doubt this presentation was exactly what some viewers needed:  it provided a summary of the printed data, in a format that some may find more accessible or interesting.  I also appreciate that, just as Cornell provides an essentially neutral home for other governmental materials, such as the United States Code, so also EDI may see its role in this regard as one of simply serving as a mouthpiece for the government.  But I was disappointed.  I hoped to hear the inside dope.  I didn’t want to just hear, without elaboration, that the 2008 ACS asked significantly different questions than previous years’ surveys, and that the resulting data are therefore not directly comparable to previous years’ results.  I already knew that; my previous post says so.  I wanted to hear why.

I wanted to hear, for example, that my own previous post was correct in its hunch that the data collection process was deliberately corrupted by the Bush Administration, in ways that no self-respecting statistician of disabilities can tolerate.  Or, alternately, I wanted to hear that, no, there were in fact very good reasons, beyond those I already surmised, for eviscerating year-to-year comparability.  I did not want to hear someone simply parrot the fact that, because of said evisceration, the loss of millions of Americans from the lists of the disabled did not mean that those people had actually ceased to have disabilities.  I wanted to hear that statisticians are taking countermeasures, in a bid to develop an approach that will give us an actual, halfway meaningful statistic on the prevalence of disabilities, and on other disability-related matters that the ACS should be covering.

Cornell ILR EDI 2008 Disability Status Reports

The Employment and Disability Institute (EDI) within the ILR School at Cornell University has now rolled out its Disability Status Reports on the American Community Survey (ACS) data for 2008.  These reports are available in PDF format for each state and also for the U.S. a whole.  Based on a review of a few such reports, it appears that each is a 65-page document covering the same list of topics, as presented in each report's list of contents.  (Note that the contents list items are clickable; for example, clicking on the line for "Prevalence:  All Ages" takes you immediately to page 10 of the report.)  Those topics are presented under two main headings, as follows:


Demographics
Prevalence: All Ages
Prevalence: Ages 4 and under
Prevalence: Ages 5 to 15
Prevalence: Ages 16 to 20
Prevalence: Ages 21 to 64 (Working-Age)
Prevalence: Ages 65 to 74
Prevalence: Ages 75 and Older
Prevalence: Gender and Age
Prevalence: Hispanic / Latino Origin and Age
Prevalence: Race

Outcomes
Employment
Not Working but Actively Looking for Work
Full-Time / Full-Year Employment
Annual Earnings (Full-Time / Full-Year workers)
Annual Household Income
Poverty
Supplemental Security Income (SSI)
Education: High School Diploma / Equivalent
Education: Some College / Associate's Degree
Education: Bachelor's Degree or More
Veterans Service-Connected Disability
Health Insurance Coverage
Type of Health Insurance Coverage


For example, the Employment section appears on pp. 32-33, apparently using virtually identical text and identically formatted graphs in each report, so that the first bulleted point on page 32 reads as follows in, say, the Michigan report.  I offer editorial comments on these reports in a contemporaneous post.

In 2008, the employment rate of working-age people with disabilities in MI was 33.6 percent.

whereas the Indiana report differs only by ending that first bulleted point with the words “in IN was 39.8 percent.”  In short, the reports provide a state-by-state, plain-English summary of key points that one will hopefully soon be able to obtain directly from the Census Bureau’s American FactFinder webpage for disability statistics.  (Note that EDI’s Disability Statistics webpage also links to disability data from the decennial Census and the Current Population Survey (CPS).

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.

American Community Survey (2003): Disabilities on the State Level

In a previous post, I examined some statistics provided by the American Community Survey (ACS) for 2003, regarding the prevalence of certain kinds of disabilities on the national level.  Now I turn to the interpretation of the ACS on the state level.

Generally, as a Census Bureau methodological report explains, state population estimates are obtained by adding up the estimated numbers of people in each county.  The calculation of county population begins with the decennial census.  At present, that is the census taken in 2000, but of course there will be a new one this year (2010).  The Bureau makes adjustments from the previous year based on a variety of county-level sources, including tax records, estimates of migration, and registered births and deaths.  Previous years' estimates are revised as new information sheds light on actual developments.

State totals are not added up to produce the national population, however.  Instead, national totals are developed independently, and are used as a check upon county-level calculations.  Roughly speaking, if the sum of all state totals (that is, the sum of all county totals) were to exceed the independently developed national population estimate by 3%, then the population estimates for all counties would be reduced by 3% so that the state totals would match the national estimate.

Given this information, a lay reader might suggest that a parallel method of estimating the prevalence of disabilities within a county -- and thus within a state -- would supplement the ACS questionnaire by investigating actual records of disabilities, from such sources as hospital and school records, handicap-plate motor vehicle registrations, and Social Security records.  Presumably the efforts of researchers have uncovered shortcomings in decennial censuses; one might expect that these sorts of disability-related investigations would exert a similar beneficial influence on ACS disability estimates.

According to Weathers (2005, p. 61), the Census Bureau does investigate ways in which its statistical processes may produce errors.  Errors may be random, in which case statistical adjustments can be made or estimates of error can be produced.  Errors may also be nonrandom.  Nonrandom errors are also called systematic errors.  These occur, not because (for example) a predictable percentage of statistical typists will make a predictable percentage of typographical errors as they enter the data, but because some kind of atypical distortion occurs with respect to some particular kind of person or situation.  If, for example, followers of a certain religion were concentrated in a particular county, and if their religion taught that it was wrong to respond to surveys, then there could be a pronounced systematic, nonrandom undercounting of people in that county.  Along these lines, it would certainly seem that people who have physical disabilities that make every task a chore, or mental disabilities that discourage cooperation with governmental surveys they perceive as suspicious, could be systematically undercounted.

Weathers (2005, p. 61) indicates that the Census Bureau maintains information on identified systematic errors in the ACS at a page on its website.  A quick search of that webpage finds, at present, no entries pertaining to disabilities.  Weathers (pp. 68-70) does note certain regards, however, in which a redesign of the ACS disability questions resulted in dramatic and potentially erroneous declines in reported disabilities in 2003.  There have been substantial changes in the ACS measurement of disabilities since then.  A subsequent post will discuss those changes.  First, however, the following paragraphs explore the 2003 ACS in light of Weathers's comments, many of which are still applicable and/or have not yet been revisited.

ACS 2003 state-by-state disability prevalence rates (Weathers, 2005, pp. 45-46) raised questions of consistency in data collection procedures.  In the Midwest, for example, most states were fairly similar to one another:  overall disability rates were between 11.2 and 13.3 in Ohio, Indiana, Iowa, Michigan, Wisconsin, Missouri, Kansas, and Nebraska.  Indeed, without Indiana and Ohio, the range among those states would have been in the narrow band of 11.2 to 12.4.  Yet somehow, in the middle of those states, Illinois – right next to Indiana (13.3) – somehow produced a rate of 9.2.  Certainly it is plausible that a city like Chicago would manage to accommodate its persons with disabilities better than a more rural state; but why the presence of a large city would affect disability prevalence itself is not intuitively obvious.  If population density itself were a positive factor, Rhode Island (12.0) would not have had a rate considerably higher than those of its neighbors Connecticut (9.2) and Massachusetts (9.7).

Certainly the 2003 ACS state-level data are interesting.  Weathers (2005, pp. 23-24) compares states in terms of the levels of employment, poverty, and household income experienced by persons with disabilities.  His tables 7-9 (pp. 47-52) also provide relative comparisons of the experiences of people with and without disabilities in those several regards.  Thus, for example, whatever the rate of unemployment in West Virginia as a whole, the data reveal that that state’s people with disabilities are employed at only about one-third (35.8%) the rate of its people without disabilities -- as compared to Wyoming, on the opposite extreme among the lower 49 states, where the rate is more like two-thirds (65.5%).  Among the midwestern states just listed (including Illinois), that relative rate ranges from 48.4% (Michigan and Ohio) to 55.8% (Nebraska).

According to Weathers (2005), the relative experience of poverty for people with disabilities, like their relative level of employment, varies considerably among states.  At the low end, people with disabilities in Utah are only 2.1 times as likely to fall below the povety line as are people without disabilities.  At the high end, people in Nebraska are 4.9 times as likely to do so.  Nebraska aside, the midwestern states listed above are within the range of 3.4 (Illinois) to 3.8 (Kansas).

As with some of the other values discussed here, relative household incomes contrast western states against southern states.  Utah leads with a value of 75.9% – that is, the median household income of a person with disabilities in Utah is 75.9% of the median household income of a person without disabilities – and Louisiana (49.6%) and Alabama (50.4%) are beaten at the bottom end only by Delaware (which, with the slightly lower value of 48.3%, is an outlier in regional terms by several of these measures).  The midwestern range is from 54.2% (Ohio) to 62.3% (Wisconsin).  Relatively large differences among these states’ neighbors (e.g., 61.9% in Indiana, 56.4% in Michigan) raise the question of how state-level policies impact these numbers.

Some caveats are in order.  First, as with most of the observations in this post, it remains to be seen how these data have changed since 2003.  Note, too, that the foregoing analyses provided by Weathers (2005, p. 19) are focused upon the working-age population, ages 25-61.  Also, the ACS presents values on employment and poverty that are in some regards markedly divergent from those reported by most other national studies cited in a previous post in this series (Weathers, p. 29).

Across all age groups, Weathers (2005, pp. 20-21), notes that national counts of disabilities may be influenced by race, culture, gender, and education.  Black people comprise 13.8% of people with disabilities, as compared to 11.7% of the population without disabilities.  Hispanic people comprise 14.0% of the population without disabilities, but only 9.6% of the reported population with disabilities.  Women constitute 52.8% of the population with disabilities (versus 51% without), and are especially highly represented in disabilities involving self-care (58.9%) and going outside the home (63.6%).  People with less than a high school education account for 11.6% of people without a disability, but they account for 25.0% of people with a disability.  Disability rates may be correspondingly affected, in states that vary from the mean in any of these demographic regards.

Having provided an introduction to state-level measurement of disabilities through the ACS in 2003, largely as interpreted by Weathers (2005), the next step is to examine how ACS federal- and state-level measurements and results were changed in 2008.

American Community Survey (2003): Disabilities Nationwide

In a previous post, I took a quick look at how the total household population figure in the American Community Survey (ACS) for 2003 was calculated.  The numbers involved are not precise in every case, but the general concept appears to be that the "resident population" is divided into people who live in households and those who live in group quarters (e.g., prisons, hospitals, dormitories).  In the 2003 ACS, only households were examined.  The total number of people in the U.S. who were living in households in 2003 was estimated to be 282,909,885.  Of those, an estimated 176,395,446 fell into the traditionally defined working-age population aged 18-64.

The next thing to figure out, in moving toward statistics on disabilities at the county level, was how many of those 176,395,446 people were considered to have various kinds of disabilities.  Here, as before, I relied on the analysis of 2003 ACS data provided by Weathers (2005) in his Guide to Disability Statistics from the American Community Survey.  The previous post notes that the ACS understates disabilities when compared to some other national surveys; however, it has the advantage of being updated on the county level, and thus provides an essential stepping-stone in this investigation.

Weathers (2005) divides that total of 176,395,446 working-age people into those with (12%) and without (88%) disabilities, as defined by the ACS.  Weathers further narrows the working-age population down to the 25-61 age range, considering the 18-24 group as being of a "school-to-work transition age" and the 62-64 group as being of "early Social Security retirement age" (p. 19).  Since the 25-61 group accounts for 83% (i.e., 17,146,845) of the total of 20,609,733 people with disabilities in the larger 18-64 group (p. 54), I will tend to focus on that 25-61 group in this post.

To summarize, then, the ACS gives us, in 2003, an estimated 17,146,845 U.S. residents who lived in households (as distinct from group homes), had one or more disabilities, and fell into the 25-61 age group.  These people comprised roughly 10% of the estimated working-age (18-64) population of about 176 million.

According to Weathers (2005, p. 35), the ACS draws upon World Health Organization (WHO) concepts of impairment, activity limitation, and participation restriction, as expressed in the International Classification of Functioning, Disability and Health (ICF) (pp. 4-5).  In the ICF, Weathers says, an impairment is a significant deviation or loss in body function or structure (e.g., vision loss).  An activity limitation is difficulty in executing activities of daily living (e.g., dressing).  A participation restriction is a problem that a person may have in a life situation (e.g., lack of employer accommodation to the person's severe health condition).

As Weathers (2005, pp. 10-11, 35) describes, the ACS uses six questions to operationalize those ICF concepts.  Three of the six ask about impairments:  sensory, physical, or mental.  One asks about activity limitation, in the form of an inability to care for oneself inside one’s home.  Two ask about participation restrictions, in the form of physical, mental, or emotional conditions that prevent the person from going outside the home (e.g., to shop) or from working at a job or business.  The ACS defines disabilities as the presence of any one or more of these kinds of disability. As an example of how these questions may fail to count some disabilities, Weathers (p. 27) indicates that the question of going outside the home, used on the ACS, is narrower than the concept of Instrumental Activities of Daily Living (IADLs) used in some surveys.

The 2003 ACS data indicate that, for the 25-61 group, two of these six questions (pertaining to physical impairment and employment restriction) account for 55% of all disabilities.  Those two plus the next most frequently cited disability, regarding mental impairment, account for 70% of all disabilities in that age group.  Yet within that statement lies an interesting age-related permutation.  First, as one might expect, age is a factor in the calculation of disability under the ACS.  The data show that disability prevalence rates rise from 6.3 in the 5-17 group (that is, 6.3% of people in that age group have a disability) to 39.9 in the 65+ group (Weathers, 2005, p. 39).  At the same time, however, while those top three questions account for about 70% of disabilities in all three working age groups (i.e., 18-24, 25-61, and 62-64), the share due to mental impairments steadily declines.  Mental impairments constitute 30% of all disabilities in the 18-24 group, but only 15% in the 25-61 group and 10% in the 62-64 group.

It is not that mental impairments actually decline with age, though that may be the case for some kinds of mental impairments.  It is, rather, that mental impairments rise only slightly, from 3.7 in the 18-24 group to 5.8 in the 62-64 group.  This is quite different from the ninefold rise in physical disabilities between those two groups.  One explanation for that contrast is that the ACS may undercount mental disabilities in adults.  There is evidence of reduced awareness of mental disability on the part of adults and their primary care physicians (e.g., Surman, Wigal, & Lakes, 2009).  Undercounting of mental disabilities in adults would also be unsurprising if significant mental disabilities are incompletely conceptualized among adults (e.g., Nijmeijer et al., 2008, p. 701).

So far in this series of posts on statistics pertaining to disabilities, I have rarely gone beyond the relatively general descriptive approach provided by commentators such as Weathers (2005).  The preceding paragraph suggests, though, that a look at more critical or focused literature may highlight a number of shortcomings with the ACS, for purposes of counting disabilities.  As an example of another area in which a more refined approach may considerably enhance the statistical picture, one may review Weathers's remark (above) about the refinement that the IADL concept adds to the question of going outside the home.  Unless Weathers meant to contrast IADL against the ACS's question regarding self-care, and simply misspeaks on that point (compare pp. 27 and 39), it seems appropriate to question the finding that 6.9% of people in the 25-61 age group experience a significant employment restriction due to disability, and yet only 2.0% report a limitation in their self-care activity.  Without a boss or other reminder of a set goal, people at home may be more likely to adjust their goals and lives to accommodate their disabilities.

Those examples of potential shortcomings in the ACS may or may not be borne out in the professional literature.  I can't say; I haven't gotten that far yet.  The purpose of those remarks was simply to highlight a few ways in which the ACS may undercount disabilities.  Having achieved that, the next step in this investigation is to move from the national-level ACS data to the state level.

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.

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.

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.