Here's a nice CBO analysis of the issue
Posted on: May 17, 2012 at 09:36:45 CT
Federal workers tend to be older, more educated, and more concentrated in professional occupations than private-sector workers.
It also has a nice breakdown by education. At the college educated group, pay is equal, at master's degree, it's lower and at professional degree or PhD it's much lower. The study does account for benefits, as it should. But remember, that's assuming you applied those benefits over a lifetime. It's trading short term pay for long term benefits, which not everyone will trade.
Furthermore, I imagine this further breaks down when you account compare government workers to large employers, which tend to pay better and provide more benefits.