The development of questions on disability for the Current Population Survey
The CPS, a monthly survey of about 60,000 households that is conducted by the Census Bureau for BLS, collects information on labor force status by a variety of demographic characteristics. The CPS was chosen as the vehicle for including the disability questions for two main reasons. First, because the CPS is a monthly survey, it would satisfy the requirement in the Executive order to present the data on disability in a timely fashion. Second, because the CPS is already the official source of employment and unemployment data for various demographic groups, it was a logical decision that data on individuals with disabilities be included within its scope.
The main purpose of the CPS is to ascertain the labor force status of the U.S. population. In addition, the CPS collects a wide range of demographic and labor force information, and answering all of its questions places a time burden on respondents, who are volunteer participants. Thus, any new question would increase the respondent burden and might cause some respondents not to participate in the survey. Moreover, because the same households may be interviewed more than once, future responses also could be affected. Complicating matters further, testing established that the measurement of disability status would require multiple questions, and asking about disabilities might be particularly sensitive for some demographic groups. In light of these difficulties, the ERMM Work Group decided that the questions on disability should be few while still meeting the requirements set forth in the Executive order.
Using the National Comorbidity Survey to test the questions
The ERMM Work Group undertook a summary review of existing disability questions and found that little testing had been done on those questions. The limited evidence available showed that the questions did not work well and yielded results that were difficult to interpret. Given the absence of a consensus on which questions could best identify the disability status of individuals, BLS worked with several academic researchers to identify surveys from which to draw questions. These surveys were selected because they were nationally known, their disability questions had face validity, or the data collected from their respondents were widely reported. The surveys ultimately chosen for disability questions were the Survey of Income and Program Participation, the National Health Interview Survey on Disability, the World Health Organization Disability Assessment Scale, the Census 2000, the National Organization on Disability’s Harris poll, and the Behavioral Risk Factor Surveillance System Quality of Life Module. The investigation resulted in a large number of potential questions, which BLS survey methodologists and subject-matter specialists evaluated to identify the ones that might work well in the CPS and to eliminate those which were unsuitable.
While the process of narrowing the list of candidate questions continued, BLS identified a test vehicle. The National Comorbidity Survey (NCS), a nationally representative survey fielded by the Department of Health Care Policy of Harvard Medical School, is funded primarily by the National Institute of Mental Health and contains extensive questions on mental health. The survey also has many questions on physical well-being and contains the Global Assessment Schedule from the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders. The questions on mental health in particular were considered important because research conducted for the ERMM Work Group showed that it is difficult to identify individuals with mental health difficulties in a survey. These individuals may appear outwardly to have no disability despite the fact that their condition affects many areas of their daily living.