Table 5.1 Alternative Estimates of the Population and the Percentage Net Undercount, April 2000 (Original March 2001 A.C.E., Base DA, Alternate DA)


Population (in millions)

Estimate of Percentage Net Undercount

Census Count


A.C.E. Estimate (Original, March 2001)



Base Demographic Analysisa



Alternate Demographic Analysisb



NOTES: All estimates include the household population (273.6 million people), the group quarters population (about 7.3 million people), and people enumerated in special operations not included in the A.C.E. (e.g., the remote Alaska enumeration). The percentage net undercount is calculated as the population estimate minus the census count divided by the estimate. Minus sign (–) indicates a net overcount of the population.

a The base demographic analysis estimate was made available in January 2001; it assumes about 6.0 million undocumented immigrants living in the United States under age 65 in April 2000—3.3 million from the 1990 DA estimate plus a net increase during the 1990s of 2.7 million.

b The alternate demographic analysis estimate was made available in March 2001; it assumes a net increase in illegal immigration during the 1990s of 5.4 million for a total of 8.7 million undocumented immigrants as of April 2000.

SOURCE: Robinson (2001a:Table 3).

In addition to the discrepancies between the A.C.E., demographic analysis, and census results, the ESCAP report cited several areas of concern about A.C.E. operations that might have affected dual-systems estimation as reasons for recommending against adjustment for redistricting purposes. It questioned the level of balancing error that may have occurred in the targeted extended search procedure. (Balancing error occurs when different criteria, such as different areas of search, are used in processing the P-sample and E-sample.) It also questioned the level of synthetic error that may have occurred for the poststrata DSE estimates. (Synthetic error occurs when the people included in a poststratum—who are intended to have the same likelihood of being included in the census or the A.C.E.—are in fact not sufficiently similar in this respect.) The report also considered the late additions to the census and cases of people who required whole-person (or whole-household)

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