Tag: output gap

The output gap is defined as ‘the difference between actual and potential output.’ When actual output exceeds potential output, the gap is positive. When actual output is less than potential output, the gap is negative. The size of the output gap traces the course of the business cycle. In the current recession, the output gap is negative in all major economies. The worry in recent months has been that a persistent large negative gap could lead to a downward deflationary spiral. Evidence is emerging, however, that the recession may be bottoming out and the danger of deflation easing. But just how big is the current negative output gap? As the article below from The Economist states, “Estimating how big the output gap is, and how much of a deflationary threat it still poses, is not easy.”

So how is the output gap measured in practice? How do we measure ‘potential output’? The two articles consider this issue of measurement and the relationship between the output gap and the rate of inflation. The last two links are to data sources giving estimates of the output gap. The first is from the European Commission and the second is from the OECD. As you will see, there are differences in their estimates.

Put out: Uncertainty over the size of the output gap complicates the task of central banks The Economist (2/7/09)
How big is the output gap? FRBSF Economic Letter (12/6/09)

See also:
Box 1.3.2 on page 31 and Table 13 on page 140 of European Economy: Economic Forecast, Spring 2009 European Commission, Economic and Financial Affairs (From the above link, click on the little ‘en’ symbol.)

and: Table 10 from OECD Economic Outlook No. 85, June 2009 OECD (From the above link, click on ‘Demand and output’. The first 10 tables then download as an Excel file.)


  1. Why is it difficult to measure potential output? (See both The Economist article and Box 1.3.2 from the European Economy: Economic Forecast, Spring 2009.)
  2. What is meant by the ‘NAIRU’? Why may it have risen during the recession? How would you set about estimating the value of the NAIRU?
  3. How might you infer the size of the output gap from the behaviour of inflation?
  4. Plot the output gap for two countries of your choice using data from both the European Economy and the OECD Economic Outlook for the years 2004 to 2010. Discuss the differences between (a) the two plots for each country and (b) the two countries.

In a recession, the government’s budget will go into cyclical deficit as tax revenue falls and government spending on unemployment and other benefits rises. Provided the deficit is purely cyclical, it can be seen as desirable since it acts as an automatic fiscal stabiliser, boosting aggregate demand and helping to pull the economy out of recession. Once the economy returns to potential national income (i.e. a zero output gap), the deficit would disappear. At potential national income (Yp), government expenditure (including benefits) will equal tax revenue. The budget is in balance.

Again, provided that the deficit is only cyclical, discretionary expansionary fiscal policy that further deepens the deficit will not be a problem for public finances in the future. Once the economy pulls out of recession, the discretionary policy can be relaxed and the higher national income will eliminate the cyclical deficit.

But the problem the Chancellor of the Exchequer faced in the Budget (on 22/4/09) was not just one of tackling the recession. The UK economy has seen a massive growth in the structural deficit. His forecast is for the total deficit to be £175bn in 2009. But, according to calculations by the Institute for Fiscal Studies, even when the recession is over and the output gap has been closed, there will still be an annual deficit of around £140bn. This is not cyclical; it’s structural.

So why is there this huge structural deficit? And what is the solution? Will the solution slow down recovery? The following articles look at the issues.

Budget 2009: Tightening the Squeeze? Institute for Fiscal Studies (23/4/09)
We should start by admitting we’ve failed as an economy: Hamish McRae Independent (22/4/09)
Budget 2009: Experts cast long shadow over Darling’s sunny outlook Guardian (23/4/09)
Budget 2009: Economist warns of spending cuts and tax rises Guardian (23/4/09)
The chancellor’s Budget dilemma: Stephanie Flanders BBC News (23/4/09)

For a global perspective on structural deficits, see:
Why the ‘green shoots’ of recovery could yet wither Financial Times (22/4/09)

Outlines of the main Budget measures can be found at:
Budget 2009: Need to know Times Online (23/4/09)
At-a-glance: Budget 2009 BBC News (22/4/09)

Full details for the Budget can be found from the Treasury’s Budget site


  1. Explain the terms ‘cyclical deficit’ and ‘structural deficit’.
  2. Draw a diagram showing how government expenditure (including benefits) and tax revenue vary with national income. The diagram should show the sitation with no structural deficit: i.e. the two lines should cross at potential national income. Illustrate (a) a cyclical deficit where actual national income is below potential national income (a negative output gap) and (b) a cyclical surplus where actual national income is above potential income (a positive output gap).
  3. Now, on the same diagram, shift the two lines to illustrate a situation of structural deficit.
  4. Consider whether the government should attempt to increase or reduce the budget deficit at a time of recession.
  5. Why has the structural deficit become so severe over the past year?
  6. How quickly should the government set about tackling the structural deficit?