However, a 2000 paper by Thomas Miles found "no" effect upon aggregate employment but found that adopting the implied contract exception causes use of temporary employment to rise as much as 15%. Later work by David Autor in the mid-2000s identified multiple flaws in Miles' methodology, found that the implied contract exception decreased aggregate employment 0.8 to 1.6%, and confirmed the outsourcing phenomenon identified by Miles, but also found that the tort exceptions to at-will had no statistically significant influence. Autor and colleagues later found in 2007 that the good faith exception does reduce job flows, and seems to cause labor productivity to rise but total factor productivity to drop. In other words, employers forced to find a "good faith" reason to fire an employee tend to automate operations to avoid hiring new employees, but also suffer an impact on total productivity because of the increased difficulty in discharging unproductive employees.