A Chronicle of the Application of Differential Privacy to the 2020 Census

Abstract

In this article, we chronicle the U.S. Census Bureau's development of the Disclosure Avoidance System (DAS) for the publicly released products of the 2020 Census of Population. We provide a brief history of the Census Bureau's fulfillment of its dual mission of conducting and disseminating the constitutionally mandated decennial information on the U.S. population and its promise of safeguarding the confidentiality of that information. We discuss the basis for and development of a new DAS for released data products from the 2020 Census and the evidence that emerged from various user communities on the accuracy and usability of data produced under this new DAS. We offer some assessments of this experience, the dilemmas and challenges that the Census Bureau faces for producing usable data while safeguarding the confidentiality of the information it collects, and some recommendations for addressing these challenges in the future.

Comment: The Essential Role of Policy Evaluation for the 2020 Census DisclosureAvoidance System

“…We conclude this commentary with a discussion of various factors that affect the key trade-off between data utility and privacy protection that is at the heart of the Census DAS debate. In this regard, we are in complete agreement with Hotz et al (2022) who point out that insufficient attention has been paid to this trade-off. 3 More evaluation studies like ours are needed in order to assess the impacts of different disclosure avoidance methods on the data utility of the decennial census in different policy areas.…”

“…We do not dispute that the new Census DAS builds upon this formal definition, but differential privacy is not the only definition of privacy. Privacy is a concept that has several legal, technical, and nontechnical definitions, and the courts, general public, and policymakers may not agree with differential privacy (Cormode et al, 2013;e.g., Hotz et al, 2022;Hotz & Salvo, 2022;Rubel, 2011;Solove, 2002). Indeed, a primary goal of the Census Bureau in adopting the new DAS was to prevent inference of individuals' 'private' racial information (Abowd, 2019).…”

Harnessing the Known Unknowns: Differential Privacy and the 2020 Census

“…In their capacity as co-chairs to the National Academies of Sciences, Engineering, and Medicine (NASEM) Committee of National Statistics (CNSTAT) Workshop and Expert Meetings on Census Data Quality, Hotz and Salvo (2022) chronicle the development of the Bureau's disclosure avoidance technology over the years, and the various challenges pertaining to the differential privacy revolution in 2020. Drawing from ethnographic fieldwork and theories from science and technology studies, boyd and Sarathy (2022) present a parallel story from the perspective of a variety of stakeholders.…”

Comment: The Essential Role of Policy Evaluation for the 2020 Census Disclosure Avoidance System

“…We do not dispute that the new Census DAS builds upon this formal definition, but differential privacy is not the only definition of privacy. Privacy is a concept that has several legal, technical, and non-technical definitions, and the courts, general public, and policy makers may not agree with differential privacy (Cormode et al, 2013;e.g., Hotz et al, 2022;Hotz & Salvo, 2022;Rubel, 2011;Solove, 2002). Indeed, a primary goal of the Census Bureau in adopting the new DAS was to prevent inference of individuals' "private" racial information (Abowd, 2019).…”