While the goal of SAIPE is providing estimates of numbers of people in poverty in various groups, for many purposes poverty rates are more readily interpreted. We provide these rates but regard them as inferior to the estimates of numbers of people in poverty because of the unknown quality of our estimates of the required denominators. We provide what we regard as "illustrative" confidence intervals around the poverty rates, which are computed as if the poverty universe estimates were "true", i.e., measured without error.
The state models estimate ratios of numbers of people in poverty to population, as measured in the American Community Survey (ACS), for the groups of interest. We convert these ratios to estimates of numbers of people in poverty by multiplying by demographic estimates of the population, as covered by the ACS, for these groups. The county models directly estimate logarithms of numbers of people in poverty for the groups of interest. The computation of poverty rates corresponding to the model-based county and state estimates of numbers of people in poverty requires estimates of the number of people in the relevant poverty universes. Because the poverty numbers are consistent with the ACS definitions, the poverty universes must also be. Beginning in 2006, the ACS poverty universe includes a small portion of group quarters populations, namely those in noninstitutionalized quarters, not elsewhere classified, such as emergency shelters, workers' dormitories, and so on. Residents of college dormitories, military housing, and all institutionalized group quarters population are excluded. Also, children under the age of 15 who are not related to the reference person within the household by birth, marriage or adoption (for example, foster children) are not included in the poverty universe and so are neither "in poverty" nor "not in poverty". Procedures for computing poverty universe estimates at the state and county levels for 2006 and beyond are described below.
For information on denominators used before 2006 see Denominators for State and County Poverty Rates: 2005 and Denominators for State and County Poverty Rates: 1993 - 2004.
State Level Estimates
We derive state level estimates of the poverty universes in four steps:
County Level Estimates
We derive county level estimates of the poverty universes in four steps: