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Geographic Spines in the 2020 Census Disclosure Avoidance System TopDown Algorithm
Geographic Spines in the 2020 Census Disclosure Avoidance System TopDown Algorithm
Working Paper Number CED-WP-2021-004
Introduction
The TopDown algorithm (TDA) first produces counts at the nation and then produces counts at lower geolevels (e.g.: state, county, etc.) subject to the constraint that all query answers in lower geolevels are consistent with those at higher geolevels. This paper describes the three sets of definitions of these geolevels, or the geographic spines, that are implemented in TDA. These include the standard Census geographic spine and two other spines that improve accuracy in geographic areas that are far from the standard Census spine, such as cities, towns, and/or AIAN areas. The third such spine, which is called the optimized spine, also modifies the privacy-loss budget (PLB) allocated to the entities within the geolevels, or the geounits, to ensure the PLB is used efficiently within TDA.
Page Last Revised - January 13, 2023
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