the linked data while protecting the confidentiality of individual respondents. The panel was also charged to consider alternative uses of administrative records for a reengineered SIPP that do not require actual data linking (for example, to evaluate SIPP data quality). In addition, the panel could consider aspects of the reengineered SIPP survey with regard to interview periodicity, mode of data collection, and sample source and size.
Before SIPP was initiated in the early 1980s, government experts and scholars agreed that better data on incomes and program participation were needed in order to assess and redesign social programs (see National Research Council, 1993:26-28). The major source of such data, the Current Population Survey (CPS), provided only limited information on family incomes and participation in government programs. This information was inadequate, not only because the CPS income reporting period (the previous calendar year) did not match the income reporting period for programs (the previous month in many instances), but also because the data did not allow researchers to track individuals and families over time. Experience in administering such programs as unemployment insurance and food stamps indicated that at least some program participants faced frequent changes in employment, earnings, and income, and that these changes were often associated with changes in program eligibility and participation that were important to understand.
A new survey that followed the same individuals over time, recording as many of these changes in income and program participation as possible, was therefore needed. To fill this gap, the Office of the Assistant Secretary for Planning and Evaluation and the Social Security Administration in what was then the U.S. Department of Health, Education and Welfare worked with the Census Bureau and outside researchers over a period of years to conceptualize, design, and field test survey questions and methods for a new survey. SIPP was the result.
Interviews for the first SIPP panel of households began in fall 1983, and, with a few exceptions, a SIPP panel has been in the field every year since then. Each panel consists of the members of a representative sample of households (ranging in size from 12,000 to 51,000 households at the start of a panel), who are interviewed every 4 months about their income, employment, family relationships, and program participation for each of the 4 months preceding the interview. Most panels have continued for 2-4 years. In the early years of the survey, SIPP interviewers conducted in-person interviews of sample members using paper and pencil questionnaires. At present, SIPP interviewers use computer-assisted personal interviewing (CAPI) for the first two interview waves and computer-assisted telephone interviewing (CATI) for all subsequent waves.