in 1990.2 (The 0.14 percent coefficient of variation translates into a standard error of about 0.4 million people in the original DSE total household population estimate of 277.5 million.) The coefficients of variation for the originally estimated coverage correction factors for Hispanics and non-Hispanic blacks were 0.38 and 0.40 percent, respectively, in 2000, reduced from 0.82 and 0.55 percent, respectively, in 1990 (Davis, 2001:Tables E-1, F-1). However, some poststrata had coefficients of variation as high as 6 percent in 2000, which translates into a large confidence interval around the estimate of the net undercount for these poststrata and for any geographic areas in which they are a large proportion of the population.

Three other improvements in the A.C.E. design deserve mention. First, an initial housing unit match of the independent P-sample address listing with the Master Address File (MAF) facilitated subsequent subsampling, interviewing, and matching operations. Second, the use of computer-assisted interviewing—by telephone in the first wave—facilitated timeliness of the P-sample data, which had the positive effect of reducing the percentage of movers compared with the 1990 PES (see Section 6-A.3). Third, improved matching technology and centralization of matching operations probably contributed to a higher quality of matching than achieved in 1990 (see Section 6-A.8).

Another innovation—the decision to target the search for matches and correct enumerations in surrounding blocks more narrowly in the A.C.E. than in the PES—was originally suspected of having contributed balancing errors to the original (March 2001) DSE estimates, but subsequent evaluation allayed that concern (see Section 6-A.9). The treatment of movers was more complex in the A.C.E. than in the 1990 PES, but, primarily because there were proportionately fewer movers in the A.C.E. compared with the PES, on balance, movers had no more effect on the dual-systems estimates for 2000 than on those for 1990 (see Section 6-A.3).

In retrospect, the decision to exclude the group quarters population from the A.C.E. universe (see Section 5-D.1) was unfortunate, as it precluded the development of coverage estimates for group


The coefficient of variation (CV) is the standard error of an estimate as a percentage of the estimate. The coverage correction factor, which would be used in implementing an adjustment, is the dual-systems estimate divided by the census count (including whole-person imputations and late additions); see Section 5-A.

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