enumerated household members, and there was no field follow-up when telephone follow-up was unsuccessful (see Appendix C.5).

After completion of all follow-up procedures, computer routines were used as in previous censuses, not only to impute responses for individual missing items but also to supply census records for household members that were missing all basic characteristics and for whole households when not even household size was known for the address. These imputation routines used records from neighboring households or people who matched as closely as possible whatever information was available for the household or individual requiring imputation (see Appendixes F, G, and H). The advantages expected from greater computerization of data processing included savings in cost and time to complete the data records. Also, it was expected that computer systems for editing and imputation would be better controlled and less error-prone than clerical operations.

The 2000 census computer systems for data processing appear to have worked well. Although delays in developing specific systems occurred because of the delays in determining the final census design, completion of software at the last minute appears to have had little adverse effect on the timing of other operations. Software development problems did delay the implementation of the coverage edit and telephone follow-up operation by a month (the operation began in late May instead of late April—see Appendix C.5.b). Moreover, the requirements for data processing operations were not often fully specified in advance, and much of the software was developed without adequate testing and quality assurance procedures, which put many data processing steps at risk (see Alberti, 2003:32–33; U.S. General Accounting Office, 2000a; U.S. Department of Commerce, Office of Inspector General, 1997). Fortunately, there were no actual breakdowns in the performance of critical software systems, although errors occurred in specific routines, such as the processing of information on forms obtained from enumerators about occupancy status and write-in entries for race, which are discussed below.