Yes, 'on the whole', 'all things being equal', 'comparable jobs', all that sort of thing.
http://www.statistics.gov.uk/cci/nugget.asp?id=285 'The percentage difference between the median level of full-time earnings in the public sector (£539 per week) and the private sector (£465 per week) widened over the year to April 2009, following annual increases of 3.1 per cent and 1.0 per cent respectively.' But then there is this one:
http://opinion.publicfinance.co.uk/2010/01/public-vs-private-pay-no-comparison/
In reality, the days of the public sector being 'underpaid' but having better job security and pensions have passed. Now they are not underpaid.