Monthly GDP background information

Information and guidance on the experimental monthly GPD statistics, including data sources and methodology.

Most of the results for the production sector are estimated using monthly business survey data, or other monthly data sources such as electricity supply and demand. For many of the industries within the Production sector, results can be quite volatile from month to month even after accounting for regular seasonal variations.

There is particular uncertainty in the estimates for construction sector output in Scotland due to there being very limited short-term regional data on output in the industry. At present, provisional monthly output is estimated based on the results for Great Britain as a whole, and has been adjusted using data on the relative differences in uptake of the Coronavirus Job Retention Scheme and some data available from the Business Insights and Conditions Survey (BICS). These results will remain under review and be updated when any other relevant data become available.

Estimates for much of the services sector are based on monthly business survey data, including the retail sales inquiry, or other monthly data sources including passenger transport information. Since June 2020, specific adjustments and checks have been required to account for the different timings of re-opening in Scotland compared to England and Wales, and the subsequent new restrictions introduced across parts of the UK from October onwards. The methodologies used for these adjustments remain under review and will be updated and extended as other industries fall into scope and more data become available. 

Estimates for Public Administration & Defence, Education and Health are mostly based on annual data sources which are normally forecast smoothly for Quarterly GDP. Specific adjustments have been developed to reflect the impact of COVID-19 on the provision of some public services, such as lower levels of education activity due to school closures. For changes in health service activity, provisional adjustments have been made which are broadly in line with the estimates of monthly GDP for the UK as a whole, and will be reviewed and revised over time as more data becomes available. There was a particular methodology challenge for the education sector in accounting for the 2020 school summer holiday period in monthly seasonally adjusted terms, because of the shift from schools operating with most pupils at home before the holidays and then returning to normal after the holidays. Initial estimates have been made which spread the level shift of this re-opening smoothly over the course of the holidays.

The Scottish Government has used similar methods to ONS to ensure comparisons can be made within the UK, but ONS also note that differences in the methods for estimating the output of health and education services across different countries mean GDP may be less internationally comparable during the COVID-19 pandemic and recovery than usual, so should be made with increased caution.



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