Our deliberations have led us to two general observations about the problems and issues outlined above. First, there are no conceivable changes in the collection of census data that will simultaneously meet all of the following objectives: (1) continue a highly intensive census effort, relying principally on physical enumeration and labor-intensive follow-up techniques, to overcome the consequences of a declining mail response rate; (2) provide detailed and reliable block-level data for redistricting and the Voting Rights Act; (3) provide the other housing and demographic data widely demanded for cross-tabulation at the level of small geographic areas; (4) reduce the differential undercount; and (5) keep costs from growing rapidly. There is, in short, no magic bullet.

Second, from an inspection of recent trends in census costs, the panel concludes that efforts to increase differential coverage, especially through highly labor-intensive enumeration techniques, are a key factor driving up costs. Moreover, efforts to improve differential coverage (i.e., the percentage difference of population counted for whites and minorities) have had increasingly diminishing returns (coverage was better in 1980 than 1970, but there were no such gains in 1990). Differential coverage improvement efforts have been carried to the point at which additional effort and expense may yield little or no improvement in coverage or in decreasing subgroup differences in net undercount. Expensive efforts to improve census coverage are understandable given such forces as the impetus of the Voting Rights Act to provide detailed data on race and ethnicity at the block level. Nonetheless, it is appropriate to ask if this continued effort to improve differential coverage, which has been so far unsuccessful and has increased census costs, is necessary for future censuses.



The denominator for census mail response rates includes both unoccupied and occupied housing units.


Overall mail response rates were 78 percent in 1970, 75 percent in 1980, and 65 percent in 1990 (U.S. General Accounting Office, 1992). If mail response rates dropped at the rate of change of 1970 to 1990, then the projected response rate in 2000 would be 55 percent.


The GAO calculation assumes continued population and household growth during the decade and a decrease in the mail response rate from 65 to a range of 55 to 59 percent, involving about 50 million nonrespondent households.


Examining census costs and the national net undercount rate over the 1960 to 1990 period, the general trend has been moderate improvements in overall coverage accompanied by substantial cost increases. The 1980 census seems atypical in the overall trend, achieving a much lower overall net undercount rate but doubling real costs per household. After the achievements of the 1980 census, the 1990 census was not able to continue the general trend of coverage improvements.

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