英国国家经济和社会研究所-英国GDP月度预测的新证据（英）

National Institute UK Economic Outlook – Summer 2025 National Institute of Economic and Social Research 1Box A: New Evidence on Nowcasting Monthly UK GDPBy Paula Bejarano Carbo, Rory Macqueen and Efthymios Xylangouras The Office for National Statistics (ONS) publishes a monthly estimate of gross domestic product (GDP) at a lag of around 40 days from the end of the month, reflecting the time it takes to collate data on economic output. At the same time, policymakers and businesses have an interest in knowing how the UK economy is performing as quickly as possible, especially during times of crisis. As a result, nowcasting – or forecasting in real time – GDP as accurately as possible is highly important. Since 2018, NIESR has produced its monthly GDP ‘tracker’ on the ONS GDP estimate release date, commenting on the latest data point and producing a ‘bottom-up’ forecast (i.e. constructed by aggregating sectoral forecasts) of economic output up to the end of the next quarter (Kara et al., 2018). In Bejarano Carbo et al. (2025), we develop this further, in light of new data series available since the pandemic, and the increasing demand for timely sectoral nowcasts. This article provides an overview of the methodology and results in Bejarano Carbo et al. (2025). We use a large dataset of public- and private-sector variables, including newly available ‘real time indicators’, as inputs to 28 nowcasting models. Each of these models is estimated for 20 industrial sectors to generate sectoral GVA nowcasts, which are then aggregated to produce a nowcast for overall GDP. We then apply empirical algorithms to combine the sectoral nowcasts, hoping to generate better GDP nowcasts by putting more weight on nowcasts from models which have been more accurate previously. By analysing how the different models and model combination algorithms perform over our sample of 57 months covering before, during and after the Covid-19 shock, we provide new evidence on nowcasting UK GDP. DataOur forecast variable of interest is the month-on-month growth rate of UK gross value added (GVA). Our nowcast is constructed indirectly from the bottom up, by nowcasting month-on-month growth rates for each of the twenty constituent industrial sectors of GVA (e.g. agriculture, construction, manufacturing, wholesale and retail trade, etc.). In twenty independent nowcasts, therefore, the target variable is the monthly growth rate of activity in the sector in question. We produce one-month-ahead pseudo-out-of-sample nowcasts – meaning that for each of our 57 test period months from June 2019 to March 2024, we generate a forecast for the upcoming publication month based on data which would have been available one month before first release. For example, the first estimate of January 2024 GDP was published on 14 March 2024; our pseudo out-of-sample nowcast is conditional on data available by 13 February 2024 (after the first estimate of December 2023 GDP was published).National Institute UK Econ