collection and processing procedures, etc.—to determine whether and what kinds of major changes may be needed. The Census Bureau is also exploring the concept of using SIPP, CPS, and administrative records data to improve the quality of income statistics (see further discussion, below).

All aspects of the current CPS and SIPP design and data collection procedures affect the quality and utility of the data for microsimulation modeling of income support programs.

This section covers population coverage, household and individual nonresponse, item nonresponse, reporting errors, sample size, and timing of data delivery.

It is well known among survey statisticians that household surveys rarely cover the population as well as the decennial census (see Citro and Cohen, 1985; Shapiro and Kostanich, 1988). The CPS and the SIPP are no exceptions to this pattern. Table 1 shows “coverage ratios” for the March 1984 and 1986 CPS and SIPP by age, race, and sex. A coverage ratio is the ratio of the population estimated from the survey, after application of the sampling weights (the reciprocal of the sampling fraction), including adjustments for nonresponse, to the population estimated from the most recent decennial census updated by vital records on births, deaths, and net immigration.

Overall, the March 1984 CPS covered an estimated 84 percent of black males and 90 percent of black females, compared with 92 percent of all other males and 94 percent of all other females. The March 1984 SIPP coverage ratios were about the same—85 percent of black males and 92 percent of black females, compared with 91 percent of all other males and 93 percent of all other females. For the CPS, coverage ratios for blacks were slightly lower for March 1986 (compared with the March 1984 CPS)—82 percent of black males and 89 percent of black females in 1986—and about the same in the two years for whites. The March 1986 SIPP showed the same decline for blacks compared with 1984—coverage ratios were 80 percent for black males and 89 percent for black females in 1986—while the SIPP showed coverage improvements for whites between the two years. Black males have the lowest coverage ratios overall, and, by age, black men in the 20–39 age categories are generally the worst-covered subgroups.

The Census Bureau uses ratio-estimation procedures to adjust the survey weights for population undercoverage in both the CPS and the SIPP. The weights are adjusted so that the population estimated from each survey agrees with the updated decennial census-based population estimates by age, sex, race, and

Front Matter (R1-R4)

Contents (R5-R8)

Introduction (1-8)

Databases and Methods of Data Enhancement (9-86)

Model Design (87-138)

Computing Technology (139-234)

Model Validation (235-330)

Model Documentation (331-351)