In Sampling and the Census: A Case against the Proposed Adjustments for Undercount, Kenneth Darga reveals that the sample survey to measure undercount has two fundamental shortcomings. It misses many of the same people who are missed by the census--estimated at 1.8 percent in Census 1990. The survey also counts as missing people who were counted by the census.

"Even sampling, an otherwise valid statistical technique, tends to produce faulty results when it relies on faulty data and faulty assumptions," argues Darga, a senior demographer at the Michigan Department of Management and Budget.

He warns that a decline in accuracy would be very serious because of the many important uses of census data. Adjustments, which affect reapportionment and redistricting, could play a small but important role in determining the partisan balance of the House of Representatives in the next decade. They could also influence the distribution of billions of dollars of public funds each year.

The census is also a primary source of information on social and economic trends. It enables scholars, government officials, business people, planners, and citizens to understand trends and developments in individual communities as well as in the nation as a whole. Census data are used for planning and analysis in such diverse fields as health, transportation, economic development, agriculture, and environmental quality.

Inaccuracy is not the only problem with the proposed census sampling. It has important legal aspects, too, because the census is mandated by the Constitution and because it has been the subject of legislation and litigation.