In economics the questions are always the same - only the answers change:

Estimated impact on GDP of a permanent increase in government purchases of 1 percent of GDP (Cogan et al.):
Cogan et al. (Feb 2009) conclude:

In this paper we used a modern empirical approach to estimate government spending multipliers.. We focused on an empirically estimated macroeconomic model - the Smets-Wouters model - recently published in the AER.

We find that the government spending multipliers from permanent increases in federal government purchases are much less in new Keynesian models than in old Keynesian models. The differences are even larger when one estimates the impacts of the actual path of government purchases in fiscal packages, such as the one enacted in Feb 2009 in the US or similar ones discussed in other countries. The multipliers are less than 1 as consumption and investment are crowded out. The impact in the first year is very small. And as the government purchases decline in the later years of the simulation, the multiplier turns negative.

The estimates reported here of the impact of such packages are in stark contrast to those reported in the paper by Christina Romer and Jared Bernstein.

Crowding out of consumption and investment in the Feb 2009 stimulus legislation: