New data prepared for the Federal Salary Council, an advisory body on federal pay, indicate that the gap between federal and private sector pay now stands at 18.41 percent, up from the 13.37 percent reported last year at this time. The data show that the gap grew the most in the Washington, D.C. and Phoenix general schedule localities but that it increased in all of the locality pay metropolitan areas and the catchall “rest of the U.S.,” or RUS, locality outside those areas. It’s unclear, however, how much of the difference is due to actual changes in relative wages between the federal and non-federal sectors and how much is due to changes in the methods used to measure the gap. The Bureau of Labor Statistics, which does the measurement, has made several changes in its procedures in recent years designed to make the data more accurate, and several changes still are being phased in.