Next Monday (29th October), the Chancellor of the Exchequer will present his budget to the House of Commons. He is expected to present spending plans for the coming five years, based on the Office for Budgetary Responsibility (OBR)’s forecasts for GDP growth. As with any projection, these forecasts are inherently uncertain, particularly as a result of substantial lags from preliminary measures of economic activity to the final estimate. For instance, since 1993, there has been only one occasion when GDP figures were not revised a quarter after the first release. Considerable uncertainty also exists as to the exact state and prospects for the UK economy.