The October edition of the IMF World Economic Outlook is out with very strong warnings about risks to growth (full report can be found at the IMF web site). In Chapter 1 there is a nice analysis about whether in our most recent growth forecasts we have recently underestimated fiscal policy multipliers. Quoting from that chapter:
"With many economies in fiscal consolidation mode, a debate has been raging about the size of fiscal multipliers. The smaller the multipliers, the less costly the fiscal consolidation. At the same time, activity has disappointed in a number of economies undertaking fiscal consolidation. So a natural question is whether the negative short-term effects of fiscal cutbacks have been larger than expected because fiscal multipliers were underestimated."
And the answer is yes and here is my reading of what has happened. About eleven years ago there was a series of academic papers that estimated fiscal policy multipliers. The conclusion of the earlier papers is that multipliers were somewhere in the range 1-1.5. In other words, a 1% increase in government spending raised GDP by somewhere between 1% and 1.5%. This was the conclusion I reached together with my co-author back in 2001 (paper is available at my web site). This was also the conclusion of the paper written by Oliver Blanchard and Roberto Perotti written around the same time and available here. The academic literature on this issue grew very fast with a large number of papers confirming the earlier estimates but also with a set of other papers that challenge the size of fiscal multipliers. In particular, papers that used events such as wars tended to find smaller multipliers. Because this is about fiscal policy, the debate has not gone away and there are still those who believe that multipliers are close to zero or even negative (i.e. when public spending goes up, private spending goes down by the same amount).
Despite the debate, my reading of the literature up to that point was that there was a significant amount of consensus around multipliers being around or slightly above 1.
As soon as the 2008 crisis started the debate went from a simple academic discussion to an urgent policy issue. What will be the impact of fiscal stimulus? The Obama administration produced a report (co-authored by Christina Romer) that suggested multipliers around 1.5 to justify the need for fiscal policy stimulus. These multipliers were criticized by those who believed that there is no room for aggregate demand management even in the presence of a large crisis. Since then the debate has become much more ideological than academic. We have had a series of additional academic papers that, if any, suggest that multipliers are even larger than the initial estimates because of the special circumstances we are in (monetary policy stuck at the zero-lower bound and a deep recession caused by develeraging forces that reduce private demand).
But these new (and old) academic results have simply be displaced by the ideological debate that followed the fiscal policy stimulus of the 2008-2009 period, which somehow led to the conclusion that those policies did not work and that what we now needed was more austerity. And when over the last two years we forecasted GDP growth rates in the face of coordinated austerity by many governments we somehow forgot to consider that multipliers can be large.
This is what the IMF suggests now in their analysis, which, by the way, is also self critical. They look at their recent forecasts for global growth and they suggest that their model was implicitly using fiscal policy multipliers around 0.5 when measuring the impact of fiscal consolidation. Given that their GDP growth forecast has been overestimating growth, the IMF now wonders whether multipliers are higher than 0.5. The analysis in the current World Economic Outlook suggests that multipliers might be within the range 0.9 to 1.7. A range which happens to be very almost identical to the one produced by the early papers and confirmed by the most recent academic literature. It is also not far from what most economic models would predict given current economic conditions.