Digital activism is usually non-violent and works best when social media tools are combined with street-level, grass-roots organization, a U.S. study found. The findings were released Wednesday by the Digital Activism Research Project at the University of Washington, which applies rigorous empirical social science methods to the study of global digital activism. "This is the largest investigation of digital activism ever undertaken," project founder Philip Howard -- a professor of communication, information and international studies -- said. "We looked at just under 2,000 cases over a 20-year period, with a very focused look at the last two years." Project researchers reviewed news stories by citizen and professional journalists describing digital activism campaigns worldwide, the university reported Thursday. A significant finding was that digital activism tends to be non-violent, Howard said. "In the news we hear of online activism that involves anonymous or cyberterrorist hackers who cause trouble and break into systems," he said. However, he said that was 2 percent or 3 percent of all the cases, and "most of the cases are average folks with a modest policy agenda" that doesn't involve hacking or covert crime. Digital activism campaigns tend to be more successful when waged against government rather than business authorities, the study found, with effective digital activists employing a number of social media tools while governments tend to lag behind activist movements in the use of those tools. Those factors "are the magic ingredients, especially when the target is a government -- a real recipe for success," Howard said.