The Social Security Disability Insurance program (Title II of the Social Security Act (hereafter, “the Act”) and the Supplemental Security Income program (Title XVI of the Act) are the two major federal programs providing cash benefits and eligibility for medical benefits to persons with disabilities. The Social Security Disability Insurance program (SSDI) is an insurance program that provides payments to persons with disabilities based on their having been covered previously under the Social Security program. The Supplemental Security Income (SSI) program is a means-tested income assistance program for disabled, blind, and aged persons who have limited income and resources regardless of their prior participation in the labor force.
The definition of disability and the process of determining disability are the same for both programs. The Social Security Act defines disability (for adults) 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 which has lasted or expected to last for a continuous period of not less than 12 months …” (Section 223 [d]). Amendments to the Act in 1967 further specified that an individual’s physical and mental impairment(s) must be “… of such severity that he is not only unable to do his previous work but cannot, considering his age, education, and work experience, engage in any other kind of substantial gainful work which exists in the national economy, regardless of whether such work exists in the immediate area in which he
lives, or whether a specific job vacancy exists for him, or whether he would be hired if he applied for work” (Section 223 and 1614 of the Act).
During the past two decades, SSDI and SSI programs have experienced faster than expected growth. In 2000 the Social Security Administration (SSA) paid $50 billion in cash benefits to 5.0 million workers under the SSDI program. Between 1989 and 2000, the number of workers receiving SSDI benefits rose from about 2.9 million to nearly 5.0 million, an increase of almost 74 percent. Likewise, in 2000, SSA paid $19 billion in benefits to 4.0 million blind and disabled working age people under the SSI program, an increase of 74 percent between 1989 and 2000 (SSA, 2001d). To a large extent this growth reflects the increases in the number of people applying for and entering the programs and a decrease in the number leaving the programs.
Statement of the Problem
Historically the disability program has been subject to rapid increases followed by periods of decline in rates of application, awards, and terminations. These fluctuations appear to arise both from external forces and from program and policy shifts. In the future, disability policymakers must have the ability to carefully gauge the effect of any policy changes in order to avoid excessive shifts in program experience resulting from such action that may stimulate, in turn, major policy reactions in the opposite direction. The challenge for SSA is to understand the reasons for fluctuations in the growth of disability rolls in order to better manage the programs and guide the anticipated growth over the coming decades.
In 1992, the Board of Trustees of the Old Age Survivors Insurance and Disability Insurance Trust Funds requested the Department of Health and Human Services (DHHS) to conduct an analysis of the SSDI program experience to explain the rapid program growth before the Board could make any recommendation to the Congress on statutory adjustments (DHHS, 1992). The DHHS study found that although the increases in applications for adult disability benefits cannot be explained definitively, many factors may have contributed to the growth in the number of people receiving Social Security disability benefits. These factors include the economic downturn in the late 1980s and early 1990s in the United States; structural changes in the labor market; demographic trends such as changes in the size, composition, and characteristics of the working age population; changes in public policies and the types of disabling impairments that are recognized and diagnosed for disability cash benefits; and a decrease in the average age of new beneficiaries with a resulting increase
in the duration of benefits. Programmatic factors include increase in program outreach and public awareness, changes in other support programs, and cost shifting by states associated with cuts in state and locally funded general assistance and other welfare programs, and the deinstitutionalization of people with mental disorders and mental retardation and other disabilities who were previously cared for by state hospital systems.
The analysis further showed that over the years, legislative and regulatory changes and judicial interpretations of eligibility criteria also have extended the scope of the program. Many other factors also have contributed to the growth of the programs, such as incentives to apply for benefits affected by changes in the structure of alternative public and private income support programs for persons with disabilities and the increases in benefit amounts and level of substantial gainful activity allowed for people receiving disability benefits. (These factors and their impact on the growth of the disability programs are discussed further in Chapter 2.)
As a result, SSA often has been faced with large workload increases in the disability programs and consequent backlogs in processing claims and appeals. These increases, however, have not been matched by increases in administrative resources. This imbalance has resulted in significant delays in processing disability claims determinations. A study conducted by SSA (1993) of the disability claim and appeal processes found that the processing time for a claim from the initial inquiry through receiving an initial claims decision notice can take up to 155 days, and through receipt of hearing decision notice, can take as long as 550 days. However, the actual time during this period that employees devote to working directly on a claim was found to be 13 hours up to the initial decision notice and 32 hours through receipt of hearing decision notice. The need to develop extensive medical evidence in every case, delays in the receipt of required medical evidence and consultative examinations at each level, and the wait at each stage of the application process because of missing information as the case is developed, impede timely and efficient decision making (SSA, 1994a).
Errors in making denial decisions by the state Disability Determination Service (DDS) adjudicators, backlogs in appeals, and inconsistencies in decisions reached by DDS adjudicators and administrative law judges (ALJs) are also a matter of concern. The decision-making standards and procedures used by the ALJs are not always the same as those followed by the DDS adjudicators. The subjective element in the disability decision process also contributes to the differences in disability decisions made at different levels of the application process and among different states (DHHS, 1982; GAO, 1994, 1997b; Hu et al., 1997). The number of decisions being appealed for reconsideration and then approved at the higher level has increased. Over time the process has become lengthy and compli-
cated, burdened by complex policies and procedures applied at different levels, resulting in untimely and inconsistent decisions (SSA, 1994a; GAO, 1995, 1997a; SSAB, 2001).
Despite all these factors and the resulting workload increases, the procedures in the current disability process have not changed in any major way since the beginning of the SSDI program in the 1950s.
Origins of the Committee’s Study
On the basis of its analysis, DHHS concluded that to better understand the need for disability benefits in the 1990s and beyond, a survey of health and disability in the United States, similar to such surveys completed in the late 1960s and the 1970s, should be undertaken. Such a survey also could assist in estimating the future cost of the disability program. Based on these findings and conclusion, the Board of Trustees recommended that the DHHS initiate a significant research effort to establish more clearly whether the SSDI program’s rapid growth in the 1990s was a temporary or a longer-term phenomenon.
In response to this recommendation, SSA initiated research aimed at understanding the growth of disability benefit programs—the changes in the size of the potentially eligible population, changes in the behavior of potential beneficiaries with respect to applying for benefits, changes in award rates, and the length of time beneficiaries remain on the rolls (DHHS, 1992; Muller and Wheeler, 1995). A number of research projects were initiated, including staff analyses and contracts to undertake econometric analyses of the causes of disability growth using cross-sectional data; a survey of field office managers undertaken by SSA as part of the research effort to understand the changes in the application behavior of individuals who are potentially eligible for disability benefits; and the Disability Evaluation Study (DES), later renamed by SSA the National Study of Health and Activity (NSHA). SSA views NSHA as the cornerstone of its long-term disability research agenda to improve its ability to understand the growth of the disability programs and to estimate the current and projected pool of the eligible population, the number who may apply for benefits, and the number who may be awarded benefits and their characteristics. It is a complex multiyear national survey of the United States household population 18–69 years of age.
Concerns about the numerous long-standing problems and complaints relating to the disability determination process, summarized above, led the SSA leadership to fundamentally rethink the entire process for determining program eligibility and improve the quality of the service in the disability claims process. In the early 1990s, the National Performance Review, headed by Vice President Gore, also directed improvement of the
Social Security Administration’s disability process as one of the key service initiatives for the federal government (SSA, 1994a). SSA believed that significant improvements could not be achieved without fundamentally restructuring the entire claims process. In view of these numerous concerns and the agency’s recognition of the need to improve the quality of the service in the disability claims process, SSA decided to develop an ambitious long-term strategy for reengineering “… the disability determination process that would be simpler than the existing one, deliver significantly improved service to the public, remain neutral with respect to program dollar outlays, and will be more efficient to administer” (SSA, 1994a, p. 46). It further stated that “… unless SSA invests substantially more funds to research and development of the simplified disability determination methodology, the full benefits of the redesigned process … will not be possible” (p. 46).
DISABILITY DETERMINATION—STRUCTURE AND PROCESS
Disability Claims Process1
The Social Security disability claims process starts at the state Disability Determination Service where most disability decisions are made for SSA at the initial and reconsideration levels. Briefly, the claims process proceeds through a series of four stages or levels: (1) applications for benefits and preliminary screening are made at the SSA district offices; (2) disability determinations are made in state DDS agencies using federal regulations and SSA guidelines and procedures; (3) claimants whose applications are denied can have their claims reconsidered at the DDS level; and (4) if benefits are denied during the reconsideration, the claimant may request a hearing before an ALJ at the SSA. Further appeals options include a request for review of the denial decision by SSA’s Appeals Council, and then review in the federal courts.
SSA envisioned that the reengineered claims process would make efficient use of technology, eliminate fragmentation and duplication, and promote flexible use of resources. Claimants would be given understandable program information and a range of choices for filing a claim and interacting with SSA. They would deal with one contact point and would have the right to a personal interview at each level of the process. Also, the number of levels in the new claims process prior to Appeals Council
review would be consolidated from four to two, and the issues for which appeals would be allowed would be more focused. Finally, if the claim is approved, the initiation of payment would be streamlined (see Figure 1-1).
Successful reengineering depends on a number of key initiatives of a new claims process. SSA’s original plan depended on a large number of initiatives that together were intended to make the reengineered claims process function efficiently. Since then the agency has reassessed many of the reengineering initiatives and developed a revised plan that focused on eight major areas for priority attention. Four of these initiatives are testing efforts (single decision maker, adjudication officer, full process model, and disability claims manager), and four are developmental activities that SSA calls “critical enablers” (systems support, process unification, simplified decision process, and quality assurance) (SSA, 1998). Thus the redesign of the disability decision process is only one of the process changes proposed by SSA to achieve reengineering of the disability claims process.
Evaluation of Eligibility for Disability Benefits
The Current Decision Process for Initial Claims
The disability decision2 process for initial claims involves five sequential decision steps (SSA, 1994a).
In the first step, or point of decision, the SSA field office reviews the application and screens out claimants who are engaged in substantial gainful activity (SGA).3
If the claimant is not engaged in SGA, step two determines if the claimant has a medically determinable severe physical or mental impairment. The regulations define severe impairment as one that significantly limits a person’s physical or mental ability to do basic work activities.
The documented medical evidence is assessed against the medical criteria to determine whether the claimant’s impairment meets or equals the degree of severity specified in SSA’s “Listings of Impair-
ments” (Listings).4 A claimant whose impairment(s) meets or equals those found in the Listings is allowed benefits at this stage on the basis of the medical criteria.
Claimants who have impairments that are severe, but not severe enough to meet or equal those in the Listings, are evaluated to determine if the person has residual functional capacity (RFC)5 to perform past relevant work. Assessment of the RFC requires consideration of both exertional and nonexertional impairments. If a claimant is determined to be capable of performing past relevant work, the claim is denied.
The fifth and final decision step considers the claimant’s RFC in conjunction with his or her age, education, training, and work experience, commonly referred to as vocational factors, to determine if the person can perform other work that exists in significant numbers in the national economy.
Proposed Redesigned Decision Process
As stated above, the redesign of the disability decision process is only one of the many process changes proposed in the reengineered disability claims process. SSA has stated that such a redesigned decision process should
be simple to administer;
facilitate consistent application of rules at each decision level;
provide accurate and timely decisions; and
be perceived by the public as straightforward, understandable, and fair.
As envisioned by SSA, the goal of the new process was “… to focus the new decision-making approach on the functional consequences of an
individual’s medically determinable impairment(s)” (SSA, 1994a, p. 21). According to SSA, in the proposed redesigned disability decision process the presence of a medically determinable impairment will remain a necessary requirement for eligibility, as required by the current law. The proposed redesigned process, however, would focus directly on developing new ways to assess the applicant’s functional ability or inability to work as a consequence of the medical impairment and to rely on these standardized functional measures to reach decisions. Medical and technological advances and societal perceptions about work capacity of a person with disabilities appear to support a shift in emphasis from the current focus on disease conditions and medical impairments to that of functional inability. For example, people with disabilities are able to function with personal assistants and assistive devices.
The redesigned disability decision process, as conceived by SSA, involved four sequential steps for deciding if a claimant meets the definition of disability as defined in the Act.
The first step is the same as in the current process. It involves screening out applicants who are engaged in substantial gainful activity.
If the claimant is not engaged in SGA, the second step would evaluate if the applicant has a documented medically determinable physical or mental impairment. Under the proposed revision, however, a threshold “severity” requirement was no longer needed.
The third step would assess if the person’s impairment is included in an index of disabling impairments (to be developed). The index would replace the current listings of impairments. It would contain a short list of impairments of such severity that, when documented, they could be presumed to result in loss of the person’s functional ability to perform substantial gainful activity without the need to further measure the individual’s functional capacity and without reference to the person’s age, education, and previous work experience.
If the claimant’s medical impairment(s) was not in the index, the fourth and final decision step would evaluate if the individual has the functional ability to perform any substantial gainful activity. These individualized assessments of functional ability would also take into consideration the effects of the vocational factors in determining the demands of the individual’s previous work. Functional assessment instruments would be designed to measure an individual’s abilities to perform a baseline of occupational demands that include the primary dimensions of work and that exist in significant numbers in the national economy (SSA, 1994a).
The final decision step of the proposed decision process subsumed both steps four and five of the current decision process. According to SSA, this step reflects the most significant change from the current decision process. SSA assumed that under this proposed decision process, the majority of claimants would be evaluated at this point using a standardized approach to measuring functional ability to perform work. Conceptually, standardized measures of functional ability that are universally acceptable would facilitate consistent decisions regardless of the professional training of the decision makers in the decision process.
After reviewing the proposed plan for the redesign of the disability decision process, the Commissioner of SSA, Dr. Chater, concluded that those aspects of the proposal that deal with functional assessment, baseline of work, and the evaluation of age would require extensive research, testing, and deliberation with experts and consumers to determine whether they could be implemented (SSA, 1994a).
The current and proposed disability decision processes and the related research conducted by SSA are discussed in more detail in Chapter 6 of this report.
THE NATIONAL ACADEMIES STUDY
The Committee’s Charge
In response to the Commissioner’s directive, SSA launched a multiyear research effort to develop and test the feasibility, validity, reliability, and practicality of a redesigned disability determination process. SSA developed what it referred to as the research plan for the redesign of the disability decision process and a time line for its completion (SSA, 1996, 1997). In 1996, SSA requested that the Institute of Medicine (IOM), in collaboration with the Committee on National Statistics (CNSTAT) of the Division on Behavioral and Social Sciences and Education (DBSSE) of the National Research Council, conduct an independent, objective review of, and make recommendations on, the statistical design and content of the NSHA and on the approach, scientific method, adequacy, and appropriateness of the research plan for the redesign of the disability decision process. The study focuses on the working age population. The committee’s specific tasks include, but are not limited to, the following:
review the scope of work for the NSHA, request for proposal, and the design and content of the survey as proposed by the survey contractor;
review and evaluate the preliminary design of the NSHA (the protocol developed by Westat), and subsequent modifications made
by SSA, identifying statistical design, methodological and content concerns, and other outstanding issues, and making recommendations as appropriate;
review SSA’s research plan and time line for developing a new decision process for disability and offer comments and recommendations on direction to the research; and
review all completed research including, but not limited to, reviewing research into existing functional assessment instruments conducted under contract to SSA by Virginia Commonwealth University, and providing advice and recommendations for adopting or developing functional assessment instruments or protocols for the redesigned disability process and NSHA.
The IOM, in collaboration with CNSTAT, appointed a committee of 14 members representing a range of expertise related to the scope of the study. The committee held its first meeting in January 1997.
Realizing that some of the key components of the research and testing relating to the NSHA design will not be completed on schedule, SSA extended the contract period of four years for an additional two years to ensure the committee’s review and evaluation of the results of the pilot study and any consequent proposed changes in the design and instruments for the national survey and other outstanding issues. In late 1999, SSA informed the committee that it had decided to no longer actively pursue the development of the new decision process as proposed in its disability redesign plan, instead it would focus its attention at this time on making improvements within the current decision process (SSA, 1999b).
The committee executed its charge through the conduct of several activities. It reviewed and analyzed an extensive body of research literature, published and unpublished, and other documents including planning documents, internal papers, requests for proposals, relevant internal documents and unpublished papers related to the redesign and SSA’s research plan, and other material provided by SSA and other government officials during the course of the study, as well as historical documents and publications relating to the subjects under consideration. Published literature on survey design and methods, evaluation and research on labor market trends, disabilities caused by physical and mental impairments, functional measures, and other relevant topics also were reviewed.
The committee met on 12 separate occasions between early 1997 and January 2002 to deliberate on the issues outlined above. Experts were invited to address the committee on various issues at five of these meet-
ings. A listing of the committee meetings and the presenters can be found in Appendix A. Several subcommittee meetings were held to work on specific issues.
The committee held two large workshops to augment its knowledge and expertise by more focused discussion on specific issues of concern, and to obtain input from a wide range of researchers and other interested members of the public:
The Workshop on Functional Capacity and Work was held on June 4–5, 1998.
The Workshop on Survey Measurement of Work Disability was held on May 27–28, 1999.
The agendas, presenters, and discussants for both of these workshops can be found in Appendix B. Reports of the workshop deliberations were published (IOM, 1999a, 2000).
In order to provide timely advice to SSA as it developed its research and its survey method and content, the committee issued fast-track interim reports on specific targeted topics that needed immediate attention by SSA. Three such reports were issued:
Disability Evaluation Study Design. First Interim Report (IOM, 1997)
The Social Security Administration’s Disability Decision Process: A Framework for Research. Second Interim Report (IOM, 1998)
Review of the Disability Evaluation Study Design. Third Interim Report (IOM, 1999b)
The first interim report was limited to an examination of the general features of the proposed survey design, data collection plans, coverage, and sampling as described in the scope of work dated July 30, 1996 (SSA, 1996), in the draft request for proposals (RFP) developed by SSA for a contract to conduct the survey. The committee made no attempt in that report to comment on the content of the questionnaires, specific measures of functional capability, or the content of the medical examinations and medical and diagnostic tests proposed for the survey.
The second interim report was a preliminary assessment of the adequacy of SSA’s research plan for developing a new disability decision process and the time line for its completion. In that context, the report outlined a framework for a research design and reviewed the general features and directions specified by SSA in the scope of work in the relevant requests for proposals for the conduct of the research. It identified critical elements of a research design that were missing from SSA’s current plans, and offered suggestions for changes in priorities and improve-
ments in the research projects already under way and others yet to be developed.
The third interim report was related directly to one of the contract tasks—review of the design, approach, and content of the survey, as proposed by SSA’s contractor for the survey, Westat, Inc. The report was a brief review of sample design, including that of the pilot study, instruments and procedures, and response rates goals developed by the survey contractor, Westat, and provided to the committee by SSA in June 1999 for its review and recommendations (Westat, 1999a,b,c). The report also commented on the proposed time line for initiation of each phase of the survey.
Detailed technical recommendations made by the committee in these interim reports are listed in Appendix C. The recommendations in the final report build on those of the interim reports.
To avail itself of expert and detailed analysis of some of the key issues beyond the time and resources of its members, the committee commissioned five background papers listed below from experts in areas of concept and measurement of disability, survey design and method, mental impairments, and disability and the labor market:
“Conceptual Issues in the Measurement of Work Disability,” by Alan Jette, Ph.D. and Elizabeth Badley, M.D.
“Methodological Issues in the Measurement of Work Disability,” by Nancy Mathiowetz, Ph.D.
“SSA’s Disability Determination of Mental Impairments: A Review Toward an Agenda for Research,” by Cille Kennedy, Ph.D.
“Survey Design Options for the Measurement of Persons with Work Disabilities,” by Nancy Mathiowetz, Ph.D.
“Persons with Disabilities and Demands of the Contemporary Labor Market,” by Edward Yelin, Ph.D., and Laura Trupin, MPH.
The full text of these papers is included in Part II of this report.
SCOPE AND LIMITATIONS
The scope of the present study is broad, consisting of two components: (1) ongoing detailed review and advice on the design, methods, sampling and content of a major complex survey of disability, and (2) a review of the research plan and the individual research projects undertaken by SSA to guide it in redesigning the disability decision process. The statistical design, methods, and content of the NSHA and the research plan for the redesign of the disability decision process represent two separate subject areas of study, each with different issues. For the
most part, therefore, they are discussed separately in this report. The study component relating to the redesign initiative is limited to the review and advice on the research being conducted and planned for the redesign of the disability decision process, which is only one element of SSA’s total effort to reengineer the disability claims process.6 The scope and extent of the review of survey plans, as well as the redesign research plans and individual research projects, were dependent on what was initiated or completed and made available by SSA to the committee during the course of the study.
Defining Work Disability
Agreement does not exist on how to define and measure disability (Frey, 1984; Kennedy and Gruenberg, 1987; Verbrugge, 1990; Mather, 1993). There is ongoing debate about the general concept of disability, some of which is discussed in Chapter 3. SSA’s focus in both the SSDI and the SSI programs, is on work disability as defined by the Social Security Act. As stated earlier in the chapter, the Act defines disability (for adults) as inability to engage in any substantial gainful activity anywhere in the national economy by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted or is expected to last for a continuous period of not less than 12 months. An individual’s physical and mental impairment(s) must be of such severity that he or she not only is unable to do the previous work but cannot, given the person’s age, education, and work experience, engage in any other kind of substantial gainful work that exists in the national economy, regardless of whether such work exists in the immediate area in which the person lives, or whether a specific job vacancy exists, or whether they would be hired if they applied for work. The definition makes clear that these programs deal with work disability.
In recent years the concept of disability has generally shifted from a focus on diseases, conditions, and impairments to one on functional limitations caused by these factors (Adler, 1996). SSA’s definition of disability was developed in the mid-1950s at a time when a greater proportion of jobs were in manufacturing and required physical labor than is the situation today. It was therefore expected that people with severe impairments
would not be able to engage in substantial gainful activity. Over the years, many changes have occurred. As the nature of work has shifted from the manufacturing to the service sector, more severely disabled persons are able to be employed because of medical and technological advances; and in recent years the public’s attitude about the employment of people with disabilities also has changed as reflected in the Americans with Disabilities Act of 1990 (ADA). In light of these changes, critics claim that SSA’s process of determining disability has not kept pace either with the understanding of disability or with advances in medical science and changes in the organization of work.
ORGANIZATION OF THE REPORT
The committee used three criteria for judging the contents of this report and its specific recommendations. First, the topic examined should be relevant to and within the scope and purview of the committee’s charge. Second, the evidence and analysis must be sufficient to support and justify its findings and recommendations. Third, a recommendation should be attainable at reasonable cost.
The research plan for the redesign of the disability decision process and the scope, statistical design and methods, and content of the NSHA represent separate, and yet related, subject areas of study with different issues. For the most part, therefore, they are discussed separately in the report. The report summarizes as appropriate the key conclusions and recommendations made by the committee in its interim reports to SSA during the course of the study and discusses the need for, and makes recommendations for, the development and maintenance of a national system to monitor the disability programs on an ongoing basis and the conduct of research needed to improve its evaluation of eligibility for disability benefits. This report is organized in a manner responsive to the contract charge.
Chapter 2 provides a brief overview of disability trends and discusses some of the factors that may have contributed to these trends.
Chapter 3 describes the meaning of the term disability and the relationship between the generic concept of disability and the term work disability.
Chapter 4 briefly reviews the design, sample size, content, and time line of the NSHA. The chapter then discusses continuing issues in survey measurement of disability and work disability, relating them to problems encountered in the research development, design, and time line of the NSHA. Finally it lays out a program of research in survey measurement issues that need to be addressed by SSA, other federal agencies, and other
researchers and makes recommendations relating future surveys of disability and work.
Chapter 5 explores ways in which SSA could build on its experience with the NSHA to develop an ongoing disability monitoring system for Social Security programs that would provide timely information on the prevalence of disability and the characteristics and distribution of persons with disabilities. The chapter discusses the need for and elements of such a system, a brief description of possible survey partners in the development and use of the data, the essential principles for such a system, a needed advisory structure, and a suggested development and implementation strategy.
Chapter 6 summarizes the committee’s preliminary assessment undertaken early in the study of SSA’s research plan to redesign the disability decision process (IOM, 1998), and the subsequent decision by SSA to terminate this redesign effort and explore ways to incrementally improve the current process. It makes recommendations on research needed to improve the disability decision process.
The final chapter highlights some of the broad issues of analytical capacity and resource considerations to implement the recommendations embodied in this report. The chapter closes with a call for needed research that would lead to fundamental improvement in the research and administrative structure and policy in the disability programs.
Although this report addresses the specific tasks in the committee’s mandate—to review the research related to the redesign of the disability decision process and the design, scope of work, and content of the NSHA—the committee hopes that the report will provide guidance to a wider audience responsible for disability policy and to researchers concerned about enhancing the ability to measure disability in a survey context. Further, the report should contribute toward development of an efficient and cost-effective system for ongoing monitoring of the prevalence of disability in the United States to guide the future direction of disability policy.