Gross domestic product (GDP) is the standard measure we use to assess the size and health of the UK’s economy. It can be measured in three different ways:
- the production or output approach
- the expenditure approach
- the income approach
Read more about these different approaches in our UK national accounts – a guide.
GDP publication stages
GDP estimates are produced monthly, quarterly and annually as part of the revisions cycle. This is to ensure the timely release of data throughout the year.
The GDP monthly estimate consists of output data and is our most timely official estimate of economic growth. There are two publication stages for the quarterly estimates: the GDP first quarterly estimate and the quarterly national accounts. In addition to output data, the quarterly estimates also include expenditure and income data to give a fuller picture of the UK economy.
Annual GDP estimates are also published at two different stages. Annual estimates are first available once all quarterly data for a given year are available in the February first quarterly estimate.
The annual estimates are then available in the UK National Accounts, The Blue Book, which is usually published in July or October each year. These estimates are subject to a process of annual reconciliation.
The GDP revisions process
GDP figures are naturally revised at different points of the production process. The revision periods are announced one year in advance in our National Accounts Revisions Policy.
Data from the output, income and expenditure approaches are used to ensure the timely release of data, alongside the accuracy of data as estimates are updated.
Figure 1 shows how GDP data move through the monthly, quarterly and annual revisions process.
Figure 1: GDP revisions process
Source: Why GDP figures are revised from the Office for National Statistics
Download this image Figure 1: GDP revisions process
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Step 1: Monthly estimates are produced
GDP estimates are published and revised monthly in the first, second and third months of the quarter in our GDP monthly publication. These estimates use output data and are our most timely official estimates of economic growth.
Step 2: First quarterly estimate produced
Approximately 40 days after the end of the quarter, monthly GDP estimates are published as the first quarterly estimate. At this stage, 80% of output data are available for growth rate calculation. Some elements of expenditure and income data are available at this stage of the process, but with a much lower response than at the quarterly national accounts.
Step 3: Data revised to produce second quarterly estimate
The first quarterly estimate is then revised to produce the second estimate in the quarterly national accounts publication. At this stage, 93% of output data and additional data from the expenditure and income approach are available for the growth rate calculation.
Step 4: Quarterly releases published and initial annual figure calculated
For the following quarters of the year, up to three further quarterly national accounts releases are published using the latest data following steps 1 to 3. Previous quarters are updated to bring in later data, according to our National Accounts Revisions Policy.
Once data have been produced for all four quarters of a calendar year, we can calculate an initial annual GDP figure. This is published for the first time in the February first quarterly estimate publication.
Step 5: Annual GDP figure published in first Blue Book
The initial annual GDP figure is formally published in the first Blue Book publication, using the quarterly data sources but with any relevant method changes of that Blue Book applied. Supply and use balancing does not take place at this stage as our annual data sources are not fully available.
Step 6: Further quarterly releases published with revised data
Up to four further quarterly national accounts releases are published. In these publications, historical periods are further revised to include additional data.
Step 7: Second annual figure published in Blue Book revised data
The second Blue Book annual GDP figure is published. At this stage, supply and use balancing takes place, and annual and quarterly data are revised. The second time that a year goes through the annual Blue Book process is the first time it gets supply and use balanced.
Step 8: Future Blue Books are based on revised data and cycle continues
All future Blue Books are based on the data revised at step 7, while the process continues with the addition of each monthly and quarterly data point.