Center for Family and Demographic Research
Survey of Income and Program Participation (SIPP)
What is the Survey of Income and Program Participation?
The Survey of Income and Program Participation (SIPP), overseen by the U.S. Census Bureau, is a continuous series of national panels (1984-2008). The SIPP panels usually include interviews from 11,000-36,700 households with the duration of panels ranging from 2½- 4 years. The SIPP divides each panel into four subsamples and each subsample is referred to as a rotation group. These four rotation groups enter the SIPP survey at different time points. For example, for 2008 SIPP panel, the entry months for these four rotation groups are May, June, July and August of 2008, respectively. After entering the survey, respondents of these rotation groups receive either personalized visits or decentralized phone interviews at a four-month interval. When visited or interviewed, respondents provide information about their lives during the previous 4 months, which are referred to as reference months.
SIPP data have been used to generate reports on sources and amounts of income, labor force participation, and welfare program participation and eligibility. The SIPP’s core questionnaire collects monthly information on general demographic characteristics, sources of income, expenditures, and program eligibility. In addition, the SIPP has topical modules which periodically collect information on seven main areas: Health, Disability, & Physical Well-Being; Finances; Child Care & Financial Support; Education & Employment; Family & Household Characteristics & Living Conditions; Personal History; and Welfare Reform.
How do I access the SIPP data?
There are three types of data in each SIPP panel: the monthly core data, the periodic topical module data, and longitudinal panel data. All of these types of data can be downloaded from the SIPP FTP site (http://www.bls.census.gov/sipp_ftp.html), the Census DataFerrett site (http://dataferrett.census.gov/), and National Bureau of Economic Research (NBER) website (http://www.nber.org/data/sipp.html). These three sites provide different command files for reading in the data files. The SIPP FTP site provides only the SAS command files, while the other two sites provide SAS, Stata, and SPSS command files.
What preparation is needed to use SIPP data?
The DataFerrett site allows researchers to conduct simple on-line analyses of SIPP data, such as calculating averages or standard deviation, running frequencies and crosstabs, and constructing simple figures. If you are only interested in these analyses, you can conduct them on the DataFerrett website without downloading SIPP data.
If you want to conduct more complex analyses with SIPP, you will need to obtain SIPP data. The SIPP data files (from any of the three websites) are ASCII files, which are different from the formats that SAS, Stata, or SPSS use for their data. Thus, depending on what statistical software you will use, you will need to download and run the corresponding command files so that the statistical software can read in and analyze SIPP data.
How do I weight SIPP data?
A variety of weight variables have been created for SIPP data; you choice of weight variables will depend on the type of the SIPP data and/or the unit of analysis. Starting with SIPP 1996 panel, the SIPP monthly core data contains four weight variables for the reference month: (1) final weight of person; (2) final weight of household; (3) final weight of family, and (4) final weight of sub-family. The SIPP Topical Module data have one weight variable for the final weight of person measured at the 4th reference month. Finally, the longitudinal SIPP panel data has one weight variable for final weight of people in the calendar year cohort. For the SIPP panels prior to 1996, there are two additional weight variables: (1) final weight of person for the interview month and (2) final weight of household for the household.
Where can I learn more about the SIPP?
Researchers interested in using SIPP can find the updates on SIPP from the main SIPP webpage (http://www.census.gov/sipp/index.html). In addition, the most recent User Guide of SIPP is available at the census website (http://www.census.gov/sipp/usrguide.html). Furthermore, NBER provides nice documents for researchers who just start learning to use SIPP data (http://www.nber.org/data/sippinfo.html#start). Finally, Jason Fields, a family demographer working for the Census Bureau, provides a detailed PowerPoint presentation discussing sampling design and methods employed in the SIPP. He also makes useful comparisons between the SIPP and CPS data (www.bgsu.edu/offices/mc/ncmr/ppt/ICPSR-Mar-Fam.ppt). For further help using SIPP or questions about this handout please stop by the Center for Family and Demographic Research at 5 Williams Hall or email us at CFDR@bgsu.edu.