Research Discussion Paper – RDP 2026-05 Real GDP Forecasts by International Organisations

We study forecasts for real gross domestic product growth by international organisations. These forecasts influence policy decisions by international organisations and national governments, and receive significant attention from the private sector. First, we compare the accuracy of forecasters and test the rationality of forecasts using a large dataset of forecasts by four international organisations (the International Monetary Fund, the World Bank, the European Commission and the Organisation for Economic Co-operation and Development) and private-sector forecasts. Second, we derive a new decomposition of differences in forecast accuracy into contributions from disagreement and the accuracy of the average forecast. Finally, we present theoretical results and empirical evidence on two explanations for the rejection of forecast rationality: the use of conditioning assumptions and the practice of making modal forecasts.