Our analyses of the distribution of children across family type were also conducted using the 2006 ACS. In these analyses, race/ethnicity and geographic area were measured following the same procedures used in our analyses of state-level divorce statistics (described earlier). Low-income children were defined as those ages 18 and younger and living in families with incomes below 200 percent of the federal poverty level. We excluded children living in group quarters such as correctional facilities, group homes, and college dormitories.
To measure family type, we divided low-income children into six groups: (1) married-parent families, (2) families with cohabiting parents, (3) never-married single-parent families, (4) formerly married single-parent families, (5) families with neither parent present, and (6) unknown family types. These groups do not distinguish between biological parents, adoptive parents, and stepparents, because the ACS data set does not make these distinctions. We created the groups by combining information from several measures of household structure included in the data set. The ACS collects social and demographic information for all members of selected households. The person who rents or owns the residence is identified as the “householder” and the other household members are identified in relation to the householder. For example, in a four-person household consisting of a husband, wife, and their two young children, either the husband or the wife is designated the householder, the other parent is identified as the spouse of the householder, and the two children are identified as sons or daughters of the householder. With this information, we accurately identified a basic family type for 92 percent of low-income children.
The remaining 8 percent of children were classified as having “unknown” family types because we could not accurately determine whether they lived with their parents. Most of these children were from one of three types of households:
- Multigenerational Households. For households with more than two generations of family members, the ACS questionnaire does not collect enough information to accurately determine how everyone in the family is related. For example, in households consisting of a grandparent living with a child and grandchild, it is not always possible to determine that the child is a parent of the grandchild instead of an aunt or uncle. Therefore, the grandchild could be living with either one parent or neither parent.
- Multifamily Households. For households with more than one family present—for example, with two siblings living together with their children—the ACS data set designates one of the two families as the “primary” family and the other family as a related “subfamily.” The data set includes relatively detailed information concerning parent-child relationships among members of the “primary” family, but no direct measures of family relationships among members of the “subfamily.” For this reason, it is impossible to accurately determine a family type for any children in the “subfamily.”
- Households with Cohabiting Partners. For households headed by cohabiting partners, the ACS designates one partner as the “householder” and the other as the householder’s “unmarried partner.” We classified any children of the householder as living with cohabiting parents. However, we could not accurately identify a family type for any other children in the household—for example, children of the unmarried partner from a previous relationship. This issue arises because the ACS asks only how the children are related to the householder, not to the unmarried partner.
Nationally, the percentage of low-income children we classified in the category for “unknown” family types is slightly higher in urban areas (8.3 percent) than in rural areas (7.9 percent) and higher among African Americans (10.9 percent) than among whites (6.2 percent) and Hispanics (8.9 percent). The rate also varies by state. However, because the overall percentage of low-income children in the unknown category is relatively low, this limitation should not greatly change the main conclusions readers draw from our analyses.
Our estimates of the distribution of children across family type are also subject to sampling error in the underlying survey data. To ensure that the figures are reliable, we excluded any estimates for subgroups of fewer than 5,000 people, the same approach we followed in our analyses of state-level divorce statistics (described earlier). We also excluded state-level estimates for any family-type categories that account for less than 2 percent of children in any group. The excluded estimates are reported in the tables with the symbol “NA” to indicate that the information is not available.
 “MABLE/Geocorr 2K Version 1.3 – Missouri Census Data Center.” [http://mcdc2.missouri.edu/websas/geocorr2k.html]. Accessed November 26, 2007.
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