Comparisons of institutional data and the U.S. census estimates for the same or similar time periods revealed a large undercount of AFDC recipients. For both the CPS and decennial census surveys, respondents are asked to recall earnings and other sources of income for the previous calendar year. As a result, income reporting to the Census Bureau is subject to memory error and under-reporting. Errors due to under-reporting are most pronounced for income not derived from earnings (i.e., public assistance, interest, dividends). Discrepancies between U. S. Census estimates for the public assistance population compared to actual payment records from state public assistance sources for Calendar Year 1989 are particularly troublesome and reflect important dimensions of the Census under-reporting problems. The Census Bureau reported 35,486 single mothers with children under 18 working in CY 1989. The Wisconsin Department of Revenue, however, showed that 52,888 tax returns were filed in 1993 for single parents in Milwaukee County, a considerably larger number than would ordinarily be expected from the 1990 census data just three years later. The 1990 census reported that there were 46,734 single parents in Milwaukee County with their own children under 18 years of age and that 22,584 of these families were living below poverty. During this same period, the Wisconsin Department of Health and Social Services made AFDC payments to an average of 33,000 Milwaukee County single parent cases per month, with an estimated 38,000 cases on AFDC at some time during Calendar Year 1989 and likely living below the poverty level.
Pawasarat, John, "Background Paper on Institutional Data and U.S. Census Counts of Low-Income Populations in Milwaukee County" (1995). ETI Publications. Paper 150.