The vast majority of underperforming federal workers don't get fired, according to a new survey from Vanderbilt University's Center for the Study of Democratic Institutions.

Almost two-thirds of underperforming managers are rarely or never dismissed. For underperforming non-managers, less than 70 percent are rarely dismissed.

About five percent of underperforming managers and non-managers are fired or reassigned within six months.

Thousands of federal executives took the survey, which also asked about how skilled the federal workforce is.

"The discourse on public service tends to be should government do this or do that, or should it be smaller?" Vanderbilt Political Science professor and study co-author David Lewis said. "But real problems exist for the kind of things everybody agrees government should be doing."

Federal executives have mixed feelings about the skills of their workforce, and many see plenty of room for improvement. When asked if inadequate skills are an obstacle to fulfilling the agency's core mission, 45 percent of executives said no, while 39 percent said yes. A small majority of federal executives said the skills of their workforce had improved during the executive's time working in their current role.

Lewis said the federal government needs to do more to share best practices among agencies. "There is no modern human resources management like you see in the best private sector firms," he said. He also called for more merit pay for federal workers. "We need to make it possible to hire the best people, reward and promote the best people and then retain the best people."