AN INEVITABLE TRUTH in every decennial census is that there are groups of people who are extremely difficult to count. In some cases, their living situations make it difficult to accurately gather data from them by standard enumeration techniques or even to locate them at all. In other cases, they may simply be unwilling or unable to provide accurate information even if a questionnaire reaches them. This is the first of two chapters in which we focus on groups of people who may have multiple residences (making it difficult to specify one “usual residence”) or whose ties to any fixed residence are ambiguous. In addition, we identify groups that are not explicitly covered by current census residence rules or that have historically proven difficult to count by the standard census methods and questionnaires. This listing of complex living situations is by no means exhaustive, but is intended to provide concrete examples of the breadth of difficulties in defining residence.
In each case we attempt to give some indication of what is known about the size of the group; this is important because not all the groups are the same in terms of the magnitude of the problems they present to the census count. Ultimately, as the Census Bureau and other agencies work on approaches to reach these problematic groups, some sense of prioritization is needed in order to make effective use of time and resources. However, there are cases in which no real quantitative assessment of a group’s size is possible; instead, we rely on qualitative impressions. For each group, we also indicate how the group was handled under the 2000 census residence rules as well as past censuses.1