2008 Wave 4 Section B.wpd

SUPPORTING STATEMENT

U.S. Department of Commerce

U.S. Census Bureau

2008 Panel of the Survey of Income & Program Participation,

Wave 4 Topical Modules

OMB Control No. 0607-0944

B. Collection of Information Employing Statistical Methods

1. Universe and Respondent Selection

The SIPP respondent universe is the civilian noninstitutionalized population based on the 2000 decennial census, which contains approximately 270 million individuals. The SIPP uses a multistage stratified sample of the U.S. civilian noninstitutionalized population. The first stage involves the definition and division of the United States into groups of counties called the Primary Sampling Units (PSU), which are assembled into homogeneous groups called strata. The second stage involves selection of units within the PSU.

The 2008 SIPP sample is the second sample for the SIPP to be fielded from the 2000 redesign of the sample. There are 351 PSUs in the 2000 redesigned SIPP and in sample for the 2008 Panel. The selected PSUs in the 2000 SIPP sample design cover both urban and rural areas of the United States and many were also in the 1990 SIPP sample design. PSU definitions, address lists, and area segments are all based on the 2000 decennial census.

Within each PSU living quarters (LQ) are systematically selected from lists of addresses prepared for the 2000 decennial census. Other sampling techniques are used to represent new construction, group quarters, and areas where incomplete addresses are common. Low income households were over sampled from the lists of addresses prepared for the census and from the lists of incomplete addresses. Wave 1 of the 2008 Panel sample will consist of approximately 65,300 designated LQs, of which approximately 52,900 will be occupied at the time of interview and about 45,000 will be interviewed. Each household contains an average of 2.1 eligible respondents; therefore, Wave 1 should contain approximately 94,500 survey respondents.

2. Procedures for Collecting Information

The raw sample data will be weighted to independent population controls by age, race, household type, sex, and Hispanic¹ origin categories. Estimates such as the number of people below the poverty level, number of social security recipients, and others can be derived directly from the resulting database. The estimation process will also include derivation of sampling errors which is required to test the statistical validity of the survey estimates.

The precision of an estimate is shown by the coefficient of variation (CV), which is the standard error expressed as a percentage of the estimate. Statistics such as the percentage of people in poverty (12 percent) are expected to have a CV of about 2 percent within the proposed sample design. We view the proposed sample design as the minimum required to provide reliable estimates for a variety of characteristics at the national level.

In sample households all people 15 years old and over will be interviewed using regular proxy-respondent rules. In accordance with the longitudinal rules of the survey, every effort will be made to interview the same people in Waves 2 through 13 as were interviewed in Wave 1. Sample individuals–all household members present at the first interview–who move within or reasonably close to the boundaries of the PSUs from which the 2008 SIPP sample was selected will be followed and interviewed. Individuals 15 years old or over who enter the household after Wave 1 will be interviewed. The interviewing cycle for each wave or interview period of the 2008 SIPP Panel is as follows:

Wave 1: September 1, 2008 through December 31, 2008.

Wave 2: January 1, 2009 through April 30, 2009.

Wave 3: May 1, 2009 through August 31, 2009.

Wave 4: September 1, 2009 through December 31, 2009.

Wave 5: January 1, 2010 through April 30, 2010.

Wave 6: May 1, 2010, through August 31, 2010.

Wave 7: September 1, 2010 through December 31, 2010.

Wave 8: January 2011 through April 30, 2011.

Wave 9: May 1, 2011, through August 31, 2011.

Wave 10: September 1, 2011 through December 31, 2011.

Wave 11: January 1, 2012 through April 30, 2012.

Wave 12: May 1, 2012 through August 31, 2012.

Wave 13: September 2012 through December 31, 2012.

The sample of 65,300 is systematically divided into quarters across the four months or rotations of each wave. We expect to obtain 11,250 interviews each month in

Wave 4.

A re-interview questionnaire, which checks for survey falsifications, is also administered to approximately 3,100 households in Waves 1-13. Households in re-interview are not eligible again for re-interview until the next calendar year. All

Type A non-interviews are ineligible for re-interview. Whenever possible re-interviews will be performed by telephone.

3. Methods to Maximize Response

In all SIPP Panels we make special efforts to minimize non-interviews. In each Wave every household in the active sample receives an advance letter that explains the purpose of the survey and why their cooperation is important. In Wave 1 each household is given a portfolio that contains reports created from the SIPP data and brochures informing respondents about the Census Bureau and our commitment to confidentiality. Each refusal case is sent a special refusal letter and the case is assigned for a refusal follow up by the program supervisor, senior FR, or an experienced FR.

During the 1996 and 2001 SIPP Panels the Census Bureau experimented with giving monetary incentives to households in order to maximize response. Based on results from these experiments we implemented the use of incentives in the 2004 Panel. During Wave 1 the respondents were sent the Advance Letter in a Priority mail envelope. Over the course of the 2004 Panel all of the survey households were eligible for a debit card worth $40. An incentive was offered to an eligible case if there were signs that the case was clearly planning to leave the survey. At the time the incentive was offered it was made clear that payment was conditioned on a complete response to the questionnaire.

During the 2008 Panel the Census Bureau plans to conduct an incentive experiment to compare unconditional incentives given at Wave 1 with discretionary incentives given to a limited number of reluctant respondents in all waves. The experiment consists of three groups including a control group, a $20 group, and a $40 group. The control group includes half of the households in the sample and will be designated to receive no incentive. The $20 group includes one-fourth of the households in the sample and were mailed a $20 debit card prior to their Wave 1 interview. The $40 group includes the remaining one-fourth of the households in the sample who will be eligible for a $40 discretionary incentive given to 15% of households in each wave. This incentive is conditional on completing the interview. These households will be offered a $40 debit card if the household is clearly planning to refuse to participate in the survey. At the time the incentive is offered it is made clear that payment is conditioned on a complete response to the questionnaire.

To adjust for those non-interviews that cannot be converted, a non-interview adjustment will be performed in the estimation procedure. Within the instrument techniques are used that reference data provided on the prior interview to lessen recall problems and keep interview time to a minimum.

4. Tests of Procedures

The 1995 Dress Rehearsal was an important procedural test in preparation for future SIPP/CAPI Panel surveys. The dress rehearsal examined both the revised questionnaire design and automated collection methodology. Also, we tested the re-interview questionnaire to ensure that it integrated well with the rest of the survey data collection system. The dress rehearsal represented the final stage of an extensive series of cognitive review and instrument tests in the CAPI environment. The use of a complete CAPI environment is based on numerous tests using automated technology at the Census Bureau.

5. Contacts for Statistical Aspects and Data Collection

The Census Bureau will collect and process these data. Within the Census Bureau, the following individuals should be consulted for further information on their areas of expertise:

Sample Design

Tracy Mattingly Chief, SIPP Branch

Demographic Statistical Methods Division

301-763-6445

Data Content

Robert Kominski Assistant Division Chief, Housing and Household Economic Statistics Division

301-763-2120

David Johnson Chief, Housing and Household Economic Statistics Division

301-763-6443

Data Collection and Tabulation

Patrick Benton Chief, Income Surveys Branch

Demographic Surveys Division

301-763-4618

Attachments

A. SIPP-CAPI Wave 4 Topical Module Items Booklet

B. SIPP-28405(L)–Director's Letter

C. SIPP-28003–Reminder Card

D. Economic Stimulus Topical Module Items

1Hispanics may be of any race.