Do federal workers make more than comparable private sector workers? It’s a simple question, but there’s no easy answer.

The Government Accountability Office this year reviewed six separate studies on federal pay and found varying answers. For instance, a 2011 American Enterprise Institute study found that federal workers with a high school education received 22 percent more than comparable workers outside the government. Those with graduate degrees received 3.9 percent more.

A Congressional Budget Office study early this year corroborated the AEI on the pay of workers with high school degrees, but the CBO also found that workers with professional degrees or doctorates earned 23 percent less than comparable private sector workers.

Meanwhile, the Cato Institute in 2009 concluded that federal workers make a whopping 58 percent more than private sector workers. But the study did not divide employees by skill level. And another government report, this one by the President’s Pay Agent, part of the Office of Personnel Management, found that federal employees made 24 percent less than comparable workers in the private sector and in local and state governments.

The studies used different data sources and took different approaches to comparing public and private sector pay, the GAO said, which explains the wide variation in the results. Both the AEI and CBO, for instance, took into account education, experience, occupation, locality and demographic factors. The President’s Pay Agent, however, only compared jobs. For instance, it would compare a government midlevel position with a similar private sector midlevel position without considering the qualifications of the workers in those positions.

The President’s Pay Agent study did not take benefits into account, but the five other reports did. Those five found that when benefits are factored in, a federal worker’s total compensation exceeds the private sector’s by anywhere from 16 percent to 100 percent.

According to the GAO, all this suggests that lawmakers should tread carefully when trying to make federal pay and benefit scales.

“The difference among the selected studies are such that comparing their results to help inform pay decisions is potentially problematic,” the study said.