The multiplier effect model is an extension of the basic spending multiplier model that relaxes the simplifying assumptions of that model. In doing so, it extends an identity, that was concerned with the multiplicative effect of circular monetary flows, to create a relationship between a monetary injection and the consequent change in real (inflation-corrected) GDP. The outcome, though still termed "the multiplier", is a factor that is not necessarily greater than one, and whose value is dependent upon a range of behavioural and environmental influences. Theoretical considerations suggest that the size of the multiplier is influenced by an economy's exchange rate regime, its openness to trade, the effectiveness of its monetary policy, the degree of access to credit, and the states of consumer and investor expectations. Its magnitude may be expected to depend critically upon the amount of unused capacity in an economy, and it is expected to be larger than average when the economy is in recession. Available theory provides little guidance as to the relative magnitude of those influences, however.
The fiscal multiplier is not just a component of economic forecasting models: it is also one of the determinants of fiscal policy. It determines the size of the fiscal stimulus necessary to counter a given recession. It determines the extent to which the benefits of fiscal consolidation are offset by reductions in output and employment. Also, by allowing for the resulting falls in tax revenue and rises in welfare payments, it can set a limit upon the rate of fiscal consolidation above which it would cause an increase - rather than the intended reduction - in the level of public debt.
- The technical problems of making an estimate of the current value of a country's fiscal multiplier are discussed briefly on the tutorials subpage
Economists' views about the size of the fiscal multiplier have usually been associated with their opinions about Keynesian economics - a subject on which they differ widely. The post-war consensus in favour of discretionary fiscal policy was associated with an implied assumption of a multiplier substantially above one, but the subsequent consensus in favour of the use of monetary policy implicitly assumed a fractional or negligible fiscal multiplier. When discretionary fiscal policy found favour again following the crash of 2008 (with the prospect of a recession too deep to be managed, even by reducing the short-term interest rate to its zero bound) Christine Romer advised President Obama that the fiscal stimulus then proposed would have a multiplier of about 1.6. That advice was contested at the time by Professor Barro, who argued on a priori grounds that the value would be near zero. A series of academic papers published some two years previously provided estimates in the range 1 to 1.5, and Barry Eichengreen has derived an estimate of 1.6 from study of 27 countries in the 1930s (the last time when interest rates were at or near zero) .
A fresh debate on the subject was triggered by a 2012 announcement by the International Monetary Fund that it had been underestimating the value of the fiscal multiplier. Its staff had previously come to the conclusion that on average, fiscal multipliers in the advanced economies had been near 0.5 during the thirty years prior to 2009. The 2012 announcement revealed that the same 0.5 multiplier had continued to be used for the Fund's forecasts since 2009, but that there was informal evidence to suggest that the true multipliers in that period had been in the range 0.9 to 1.7
The size of the fiscal multiplier has a decisive bearing on whether the output costs of a chosen rate of fiscal consolidation are outweighed by the investor confidence benefits of its consequent debt reduction. The assessment that they are is the implicit basis of the fiscal policy of most European countries. The possibility that assessment may have been based upon underestimates of the multiplier has raised doubts about the merits of current policy choices. It has even led some analysts to suggest that over-rapid fiscal consolidation may be self-defeating - causing increased borrowing as a result of reduced tax revenues and increased social security costs..
- Giancarlo Corsetti, Andre Meier, and Gernot J. Müller What Determines Government Spending Multipliers?, IMF Working Paper WP/12/150, June 2012
- The Effectiveness and Scope of Fiscal Stimulus, OECD Economic Outlook, March 2009
- (Then chair of his Council of Economic Advisors)
- Professor of Economics at Harvard
- Antonio Fatas and Ilian Mihov, Underestimating Fiscal Policy Multipliers, Vox, October 8 2012
- Professor of Economics and Political Science at the University of California, Berkeley
- Barry Eichengreen and Kevin H O’Rourke: Gauging the multiplier: Lessons from history, Vox, 23 October 2012
- Are We Underestimating Short-Term Fiscal Multipliers?, World Economic Outlook p41, International Monetary Fund, October 2012
- Dawn Holland and Jonathan Portes, Self-defeating austerity?, Vox, 1 November 2012
- Jocelyn Boussard, Francisco de Castro and Matteo Salto: Fiscal Multipliers and Public Debt Dynamics in Consolidations, European Commission, July 2012