Federal pay ahead of private industry
usatoday.com
usatoday.com
I think that's a pretty large discrepancy to not include in the study.
At the end of the article, state and city salaries are also mentioned. Again, a false comparison since it is on straight salary without mention of guaranteed pension and other benefits (eg. MEA members not paying SS).
IOW if you are average or below, the US govt will gladly overpay you. If you are exceptional, you will make a lot more money in the private sector.