By its very name, the 2009 American Recovery and Reinvestment Act was advertised to increase investment. Yet years before this stimulus act was proposed, Austan Goolsbee, now chairman of the President's Council of Economic Advisers, explained in his doctoral dissertation how investment tax credits might do little to stimulate investment during the life of the credit.
In at least one respect, the results of the act appear to confirm his theory.
read more about the uncertainties of tax credits in the New York Times article linked below.
http://economix.blogs.nytimes.com/2011/01/12/early-doubts-about-whether-tax-credits-stimulate-investment/
