Purpose: To collect source and amount of income, labor force information, program participation and eligibility data, and general demographic characteristics to measure the effectiveness of existing federal, state, and local programs; to estimate future costs and coverage for government programs, such as food stamps; and to provide improved statistics on the distribution of income and measures of economic well-being in the country.
Survey design and sample size: The survey design is a continuous series of national panels, with sample size ranging from approximately 14,000 to 36,700 interviewed households. The duration of each panel ranges from 2 ½ years to 4 years. The SIPP sample is a multistage-stratified sample of the U.S. civilian noninstitutionalized population. For the 1984-1993 period, a new panel of households was introduced each year in February. A 4-year 1996 panel was introduced in April 1996; a 3-year panel was started in February 2000 but cancelled after 8 months for budget reasons; and a 3-year panel was introduced in February 2001. The 2 ½ year 2004 SIPP sample was started in February 2004 and is the first SIPP panel to use the 2000 decennial-based redesign of the sample.
The SIPP content is built around a "core" of labor force, program participation, and income questions designed to measure the economic situation of people in the United States. These questions expand the data currently available on the distribution of cash and noncash income and are repeated at each wave of interviewing. The survey uses a 4-month recall period, with approximately the same number of interviews being conducted in each month of the 4-month period for each wave. Interviews are conducted by personal visit and by decentralized telephone.
The survey was designed also to provide a broader context for analysis by adding questions on a variety of topics not covered in the core section. These questions are labeled "topical modules" and are assigned to particular interviewing waves of the survey. Topics covered by the modules include personal history, child care, wealth, program eligibility, child support, utilization and cost of health care, disability, school enrollment, taxes, and annual income.
Type of respondent: All household members 15 years old and over are interviewed by self-response, if possible; proxy response is permitted when household members are not available for interviewing.
Sponsoring agency and legal authority: The U.S. Census Bureau sponsors the survey under the authority of Title 13, United States Code, Section 182.
Periodicity: A continuing survey with monthly interviewing.
Release of results: Data are released periodically in cross-sectional, topical module, and longitudinal reports. These files are available currently for all waves of the 1984 through 1993 panels, all waves of the 1996 and 2001 panels, and a preliminary wave 1 for the 2004 panel. Topical module files containing core and topical module data also are available for the 1984 through 1988 panels, 1990 through 1993 panels, the 1996 and 2001 panels. Longitudinal files are also available for the 1984 through 1993 panels, as well as for waves 1 through 5 of the 1990 panel and for waves 1 through 7 of the 1992 panel. Longitudinal files for all waves of the 1996 panel and 2001 panels are also available.
Historical background: Considerable efforts and funding were invested in developmental work leading to the SIPP. The Income Survey Development Program, conducted between 1977 and 1981, developed survey data collection strategies and instruments, as well as data processing strategies for the SIPP. The survey was originally envisioned as a jointly funded effort by the Census Bureau and the Department of Health and Human Services (HHS). Work was well underway for a February 1982 start of the survey when the HHS had to withdraw its support due to funding problems. As a result, the survey was postponed until the Census Bureau received adequate funding from Congress to conduct the survey. Interviewing for the first panel, the 1984 panel, began in October 1983 with a sample size of approximately 26,000 designated households.
As part of our transition to the redesigned SIPP, the 1992 panel was extended to ten waves, and the 1993 panel was extended to nine waves. We did not introduce new panels in 1994 and 1995. Before the redesigned SIPP questionnaire was introduced in the 1996 panel, a dress rehearsal was conducted between February 1995 and September 1995. The dress rehearsal consisted of a Wave 1 and a Wave 2 interview in approximately 9,000 households. In 1996, the SIPP Executive Committee established the Continuous Instrument Improvement Group (CIIG), consisting of staff from numerous divisions, whose task was to review and improve the SIPP core instrument. The CIIG generated an extensive set of recommendations, and the need for thorough and rigorous testing led to the creation of a methods panel, separate from the production survey. The methods panel project consisted of a small survey separate from the SIPP 2001 panel, which was experimentally designed to support rigorous testing of new alternative instrumentation. Testing took place between 1999 and 2003, including three field tests in 2000, 2001, and 2002. Field tests included a test instrument (consisting of CIIG's recommendations) and a control instrument (the SIPP 2001 production instrument). Results were compared and analyzed, and the final instruments were delivered for implementation in the 2004 panel.
Current operations: The 2004 panel began in February 2004 and consists of 46,500 households to be interviewed eight times. The SIPP interviews are conducted using a computer-assisted interview on a laptop computer.
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Page Last Modified: May 9, 2006