According to new research from the University of Southern California and Indiana University, up to 15 percent of Twitter accounts are in fact bots rather than people. Researchers at USC used more than one thousand features to identify bot accounts on Twitter, in categories including friends, tweet content and sentiment, and time between tweets. Using that framework, researchers wrote that "our estimates suggest that between 9% and 15% of active Twitter accounts are bots." Since Twitter currently has 319 million monthly active users, that translates to nearly 48 million bot accounts, using USC's high-end estimate. The report goes on to say that complex bots could have shown up as humans in their model, "making even the 15% figure a conservative estimate." At 15 percent, the evaluation is far greater than Twitter's own estimates. In a filing with the SEC last month, Twitter said that up to 8.5 percent of all active accounts contacted Twitter's servers "without any discernable additional user-initiated action." USC's researchers ... highlight the benefits of some bots, writing, "many social bots perform useful functions, such as dissemination of news and publications" But the USC report also points to the downside of bots, saying, "there is a growing record of malicious applications of social bots. Some emulate human behavior to manufacture fake grassroots political support [and] promote terrorist propaganda and recruitment."