Figure 1. Risks to Global Growth
Upside risks to global growth have increased since January while downside risks for current-year growth have reached post-crisis highs.
A 90% confidence interval implies a 90% chance of growth falling within the given range
Assessing economic forecast uncertainty and the balance of risks to the growth outlook is critical to effective policymaking. Lower-probability but high-impact events can lead to significant deviations from baseline projections, and this should be factored into policy design. The World Bank’s most recent Global Economic Prospects unveiled a tool to quantify uncertainty around global growth forecasts and presented it in the form of a fan charts (Figure 1)
The approach adopted in the Global Economic Prospects report consists of two steps.
First, a number of measurable risk indicators that are typical sources of forecast errors for global growth forecasts are selected. Three were chosen: equity price futures, oil price futures and bond term spreads (the difference between short and long term interest rates). For instance, greater volatility in oil price futures could be associated with rising uncertainty around global growth forecasts, while a downward trend in equity price futures could signal rising downside risks to growth.
Second, the probability distributions of forecasts for these three indicators are then mapped to the distribution of global growth forecasts. Both the degree of uncertainty and the balance of risks to the forecast are approximated by weighted averages of the standard deviation and skewness implied by the distributions of expectations for the risk indicators. The weights are estimated in a vector autoregression model (Ohnsorge, Some, and Stocker 2016). To account for potential asymmetry in the distributions of risks, a two-piece normal distribution is assumed, in line with other studies.