For this reason, the United States Department of Defense (DoD) has strict policies controlling release of personally identifiable information of DoD personnel. Many intelligence agencies have similar policies, sometimes to the point where employees do not disclose to their friends that they work for the agency. Similar identity protection concerns exist for witness protection programs, women's shelters, and victims of domestic violence and other threats. Trade of personal data During the second half of the 20th century, the digital revolution introduced "privacy economics", or the trade of personal data. The value of data can change over time and over different contexts. Disclosing data can reverse information asymmetry, though the costs of doing so can be unclear. In relation to companies, consumers often have "imperfect information regarding when their data is collected, with what purposes, and with what consequences." Writing in 2015, Alessandro Acquisti, Curtis Taylor and Liad Wagman identified three "waves" in the trade of personal data: In the 1970s, the Chicago Boys school claimed that protection of privacy could have a negative impact on the market because it could lead to incorrect and non-optimal decisions. Other researchers like Andrew F. Daughety and Jennifer F. Reinganum suggested that the opposite was true, and that absence of privacy would also lead to this. In the mid 1990s, Varian retook the Chicago Boys approach and added a new externality, stating that the consumer would not always have perfect information on how their own data would be used. Kenneth C. Laudon developed a model in which individuals own their data and have the ability to sell it as a product. He believed that such a system should not be regulated, to create a free market. In the 2000s, researchers worked on price discrimination (Taylor, 2004), two-sided markets (Cornière, 2011) and marketing strategies (Anderson and de Palma, 2012). The theories became complex, and showed that the impact of privacy on the economy highly depended on the context. See also Anonymity Bundesdatenschutzgesetz De-identification General Data Protection Regulation Non-personal Data Personal identifier Personal identity Personal Information Agent Protected health information Privacy Privacy law Privacy laws of the United States Pseudonymity Obfuscation Self-sovereign identity Surveillance Notes References External links Six things you need to know about the new EU privacy framework A legal analysis of the new European regulatory framework about data privacy Personal and professional information management Power to the People! Giving Citizens their Personal Data