As background to our detailed recommendations, this chapter first outlines two approaches to taking the decennial census: the traditional census and a redesigned census. The chapter then discusses the major components of the second approach, identifies the critical choices that will have to be made in designing such an approach, and makes specific recommendations for the basic strategy that should be used. The chapter then considers and recommends a number of additional measures that could improve the accuracy and lower the costs of the next census. Finally, it proposes a fundamental review and reengineering of all census procedures to take advantage of the full cost-reducing potential of the new approach.
The traditional approach, used in the 1990 census, relies completely on intensive efforts to achieve a direct count (physical enumeration) of the entire population. The alternative approach, an integrated combination of enumeration and estimation, also starts with physical enumeration, but completes the count with statistical sampling and survey techniques. Figure 5.1 is a schematic presentation of the two approaches.
The enumerative approach, labeled the traditional census on the left-hand side of the figure, begins with the construction of an address register, including elaborate procedures to improve its comprehensiveness.1 Census forms are then mailed to a comprehensive list of residential addresses, with instructions to mail back the completed questionnaire. Not all households return their completed mail questionnaire within a reasonable period of time. For households that do not respond to the mail questionnaire (35 percent of all housing units and 26 percent of all occupied housing units in 1990), census enumerators undertake an intensive follow-up effort to determine whether the unit is occupied and, if so, to contact the household and elicit responses. Repeat visits are made, administrative records are sometimes examined, and special programs to contact particular groups (e.g., homeless people) are carried out. This process is continued for an extended period of time to enumerate physically every household and all the people in every household.
Extensive special programs have been directed toward coverage improvement in recent censuses. These programs are expensive, both in absolute terms and often in terms of the cost per person or housing unit. Special coverage improvement programs have included:
movers check—a follow-up of people reporting a change of address to the U.S. Postal Service during the census enumeration period;
prelist recanvass—in prelist areas, a recheck of the address list during the second stage of follow-up;
vacant/delete check—a recheck in the field of housing units originally