Economic forecasts Roubini says that his economic approach is "holistic." Rather than focus on mathematical models and formulas, he draws his ideas from a combination of history, literature, and international politics. Roubini was one of the economists, along with among others economist Stephen Roach, analyst Meredith Whitney, and investment advisers such as Gary Shilling, Peter Schiff, and Marc Faber, and CFTC chair Brooksley Born who predicted the crash of 2007–08. He said: "I've been studying emerging markets for 20 years, and saw the same signs in the U.S. that I saw in them, which was that we were in a massive credit bubble [as 2008 approached]." He warned about a crisis in an IMF position paper in 2006. Roubini's predictions earned him the nicknames "Dr. Doom" and "permabear" (economist slang for someone who continually projects downturns) in the media. In 2008, Fortune magazine wrote, in an article entitled "Eight Who Saw it Coming . . . and eight who didn't," that in 2005 he had said home prices were “riding a speculative wave that would soon sink the economy. Back then the professor was called a Cassandra. Now he's a sage". The New York Times noted that he foresaw "homeowners defaulting on mortgages, trillions of dollars of mortgage-backed securities unraveling worldwide and the global financial system shuddering to a halt". In September 2006, he warned a skeptical IMF that "the United States was likely to face a once-in-a-lifetime housing bust, an oil shock, sharply declining consumer confidence, and, ultimately, a deep recession". Nobel laureate Paul Krugman added in 2009 that his once "seemingly outlandish" predictions were matched "or even exceeded by reality." However, financial journalist Justin Fox observed in the Harvard Business Review in 2010 that "In fact, Roubini didn’t exactly predict the crisis that began in mid-2007... Roubini spent several years predicting a very different sort of crisis — one in which foreign central banks diversifying their holdings out of Treasuries sparked a run on the dollar — only to turn in late 2006 to warning of a U.S. housing bust and a global 'hard landing'. He still didn’t give a perfectly clear or (in retrospect) accurate vision of how exactly this would play out... I’m more than a little weirded out by the status of prophet that he has been accorded since." Others noted that: "The problem is that even though he was spectacularly right on this one,