Government Employees Work Fewer Hours Than Private Sector Employees

From The Wall Street Journal, "Biggs and Richwine: The Underworked Public Employee: The cliché is true: Government workers do tend to take it easier than their private counterparts." by Andrew G Biggs and Jason Richwine:

[O]verstaffing is a serious problem in government, and the best evidence is a simple empirical fact: Government employees don't work as much as private employees. If public-sector employees just worked as many hours as their private counterparts, governments at all levels could save more than $100 billion in annual labor costs***What we found was that during a typical workweek, private-sector employees work about 41.4 hours. Federal workers, by contrast, put in 38.7 hours, and state and local government employees work 38.1 hours. In a calendar year, private-sector employees work the equivalent of 3.8 more 40-hour workweeks than federal employees and 4.7 more weeks than state and local government workers. Put another way, private employees spend around an extra month working each year compared with public employees. If the public sector worked that additional month, governments could theoretically save around $130 billion in annual labor costs without reducing services.***But could public-private differences in work time be due to other occupational differences between the sectors? Large differences in work hours actually persist even when comparing workers with similar jobs and similar skills in each sector.