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hold person weighting because the weighting for household persons makes use of the GQ person weights. The household and GQ weights are combined to produce estimates of the total population.

The first step applies a trimmed base weight that reflects the initial sampling probability and the within-GQ subsampling probability. The second step is a noninterview adjustment across group quarters, defined within state, by county and by major GQ type. If the sample is small or if the adjustment is large, the cells are collapsed to state by major GQ type. The third step applies a coverage adjustment, controlling the weighted number of GQ persons at the state level by major GQ type, using the GQ population estimates from the Population Estimates Program (PEP).

On the basis of the current estimation procedures, only the total population (households and group quarters) is guaranteed to be controlled at the county (or groups of less populous counties) level. When some small geographic areas with GQ populations do not have group quarters represented in the sample, group quarters in other areas may be overrepresented. Thus, for some small areas, the 5-year estimates do not reflect local reality.

Alternative Approach Under Consideration

The Census Bureau is researching the possibility of introducing a new imputation and weighting approach, with the primary goal of achieving representation at the county level of all major GQ types present in that county for the 1-, 3-, and 5-year data. A secondary goal is to achieve representation at the tract level by major GQ type for the 5-year data. Keeping in mind the ongoing imputation research, the new method will make no distinction between sampled and imputed GQ person records, and it is developed to be sufficiently flexible to accommodate different possible outcomes of that research (Asiala, 2011).

The alternative GQ weighting methodology is based on the steps described below (Asiala, 2011). This approach is discussed in further detail later in this chapter.

  1. Defining separate base weights for persons in large and small group quarters.
  2. Applying tract- and county-level constraints based on the modeled populations on the frame and applying state by major GQ type-level controls based on independent population estimates.

PEP CONTROLS AND ALTERNATIVES

The population controls used in the ACS weighting process are based on estimates produced by the Census Bureau’s Population Estimates Program. The PEP publishes total population estimates annually, based on a methodol-



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