Google COVID-19 Community Mobility Reports: Anonymization Process\n Description (version 1.1)

Abstract

This document describes the aggregation and anonymization process applied to\nthe initial version of Google COVID-19 Community Mobility Reports (published at\nhttp://google.com/covid19/mobility on April 2, 2020), a publicly available\nresource intended to help public health authorities understand what has changed\nin response to work-from-home, shelter-in-place, and other recommended policies\naimed at flattening the curve of the COVID-19 pandemic. Our anonymization\nprocess is designed to ensure that no personal data, including an individual's\nlocation, movement, or contacts, can be derived from the resulting metrics.\n The high-level description of the procedure is as follows: we first generate\na set of anonymized metrics from the data of Google users who opted in to\nLocation History. Then, we compute percentage changes of these metrics from a\nbaseline based on the historical part of the anonymized metrics. We then\ndiscard a subset which does not meet our bar for statistical reliability, and\nrelease the rest publicly in a format that compares the result to the private\nbaseline.\n