is possible that some of these cases—perhaps a large proportion—were erroneous or duplicates (type 2 situations could also include duplicates). Research is needed on the geographic distribution of housing status imputations, the sources of addresses for them in the MAF, and the extent to which features of the 2000 nonresponse and coverage improvement follow-up operations (e.g., instructions to enumerators) may have contributed to the larger number of such cases. Research is also needed on the quality of the housing status imputation process, which was refined somewhat from the 1990 procedure (see Appendix A). Although it may result that the housing status imputations in the 2000 census appear reasonable, it is clearly desirable to minimize the number of census enumerations for which so little is known. Hence, research on the sources of these enumerations is important to carry out for planning the 2010 census.
Research is needed on the sources and geographic distribution of the MAF addresses that necessitated the special unduplication operation in summer 2000. This operation was unprecedented. Not only did it pose a risk for census data processing, but it also meant that the A.C.E. was less informative about erroneous enumerations than if the records that were reinstated at the conclusion of the special operation had been available to include in the A.C.E. It seems desirable to preclude the necessity for any such late-occurring address clean-up operation in future censuses, which means that the Census Bureau’s plans for reengineering the MAF development process for the 2010 census are critically important (see Chapter 4).
Research is also needed on the quality of the reinstated records in 2000. Field work may be needed to estimate the extent of duplication among the reinstated records (and among some types of imputations). In addition, research is needed on the extent of duplication of people with more than one residence. A possible way to study the issue would be to use the American Community Survey to ask about multiple residences at the time of the census and then to check the census records to determine how such cases were enumerated.