Diierences between the 1990 and 2000 Census Adjustment Plans, and Their Impact on Error

A revised plan for the 2000 Decennial Census was announced in a 24 February 1999 Bureau of the Census publication 99 and a press statement b y K. Prewitt, Director of the Bureau of the Census 39. Census 2000 will include counts and adjusted" counts. The adjustments involve complicated procedures and calculations on data from a sample of blocks, extrapolated throughout the country to demographic groups called post-strata." The 2000 adjustment plan is called Accuracy and Coverage Evaluation ACE. ACE is quite similar to the 1990 adjustment plan, called the Post-Enumeration Survey PES. The 1990 PES fails some plausibility c hecks 4, 1 2 , 444 and probably would have reduced the accuracy of counts and state shares 3, 4. ACE and PES diier in sample size, data capture, timing, record matching, post-stratiication, methods to compensate for missing data, the treatment o f m o vers, and ACE improves on PES in a number of ways, including using a larger sample, using a simpler model to assign match probabilities" to records with insuucient data, and incorporating mail-back return rates into some post-strata. Nonetheless, ACE shares the most serious problems of PES. The Be Counted" program, census response submission over the internet, computer unduplication of records, the treatment o f m o vers 10, 2 5 , a new deenition of correct address," more limited search for matching records 35, the use of optical character recognition OCR to capture data 7, 8, 9 , 1 0 , 3 1 , the data collection schedule 10, and the assignment of residence probabilities" to some sample records 6, 322, are likely to make ACE less accurate than the 1990 PES.