An anonymous reader writes "In a guest post on the Patently-O blog, Villanova University professor Michael Risch summarizes his detailed study into the methods and efficacy of patent trolls. He writes, 'It turns out that most of what I thought about trolls — good or bad — was wrong.... Perhaps the biggest surprise in the study was the provenance of patents. I thought most patents came from failed startups. While such patents were represented (about 14% of initial assignees were defunct), most came from companies still in business in 2010. Indeed, more than a third of the initial assignees were publicly traded, a subsidiary of a public company, or venture capital recipients. Only 21% were patent assertion entities at the time the patent issued, and many of those were inventor owned companies (like Katz) rather than acquisition entities (like Acacia). ... Another area of surprise was patent quality. While trolls almost never won their cases if they went to judgment (only three cases led to an infringement finding on the merits), the percentage of patents invalidated on the merits was lower than I expected.'"