The 2020 Census Disclosure Avoidance System (DAS) is a formally private mechanism that first adds independent noise to cross tabulations for a set of pre-specified hierarchical geographic units, which is known as the geographic spine. After post-processing these noisy measurements, DAS outputs a formally private database with fields indicating location in the standard census geographic spine, which is defined by the United States as a whole, states, counties, census tracts, block groups, and census blocks. This paper describes how the geographic spine used internally within DAS to define the initial noisy measurements impacts accuracy of the output database. Specifically, tabulations for geographic areas tend to be most accurate for geographic areas that both 1) can be derived by aggregating together geographic units above the block geographic level of the internal spine, and 2) are closer to the geographic units of the internal spine. After describing the accuracy tradeoffs relevant to the choice of internal DAS geographic spine, we provide the settings used to define the 2020 Census production DAS runs.

翻译：2020年人口普查披露避免系统（DAS）是一种形式上的隐私保护机制，该机制首先为预先指定的分层地理单元（称为地理主干）的交叉汇总表添加独立噪声。在对这些带噪声的测量值进行后处理后，DAS输出一个形式上的隐私数据库，其中包含标注标准人口普查地理主干（由美国整体、州、县、普查区、街区组和普查区块定义）位置的字段。本文描述了DAS内部用于定义初始带噪声测量值的地理主干如何影响输出数据库的准确性。具体而言，对于既能通过聚合内部主干中高于区块地理层级之上的地理单元得到，又更接近内部主干地理单元的地理区域，其汇总表往往最为准确。在描述了与内部DAS地理主干选择相关的准确性权衡后，我们提供了用于定义2020年人口普查生产DAS运行的设置参数。