“The Berkman Klein Center is pleased to announce a new publication from the Privacy Tools project, authored by a multidisciplinary group of project collaborators from the Berkman Klein Center and the Program on Information Science at MIT Libraries. This article, titled “Practical approaches to big data privacy over time,” analyzes how privacy risks multiply as large quantities of personal data are collected over longer periods of time, draws attention to the relative weakness of data protections in the corporate and public sectors, and provides practical recommendations for protecting privacy when collecting and managing commercial and government data over extended periods of time. Increasingly, corporations and governments are collecting, analyzing, and sharing detailed information about individuals over long periods of time. Vast quantities of data from new sources and novel methods for large-scale data analysis are yielding deeper understandings of individuals’ characteristics, behavior, and relationships. It is now possible to measure human activity at more frequent intervals, collect and store data relating to longer periods of activity, and analyze data long after they were collected. These developments promise to advance the state of science, public policy, and innovation. At the same time, they are creating heightened privacy risks, by increasing the potential to link data to individuals and apply data to new uses that were unanticipated at the time of collection. Moreover, these risks multiply rapidly, through the combination of long-term data collection and accumulations of increasingly “broad” data measuring dozens or even thousands of attributes relating to an individual…”