Can public sector wage bills be reduced?

An interesting, and relevant, question asked by Pierre Cahuc and Stephane Carcillo in a new NBER working paper. The abstract reads:

This paper analyzes the relation between public wage bills and public deficits in the OECD countries from 1995 to 2009. The paper shows that fiscal drift episodes, characterized by simultaneous increases in the GDP shares of public wage bills and budget deficits, are more frequent during booms and election years, but not during recessions, except for the 2009 exceptionally strong recession. The emergence of fiscal drift episodes during booms and election years is less frequent in countries with more transparent government, more freedom of the press, as well as in countries with presidential regimes and less union coverage. Inversely, fiscal tightening episodes, characterized by simultaneous decreases in the GDP shares of public wage bills and budget deficits, occur less often during booms than during recessions. The emergence of fiscal tightening episodes during recessions and election years is less frequent in countries with more union coverage.

The last point about union coverage may be relevant to New Zealand given the power of state sector unions.