Answers to common questions about the GDP statistics.
- What is the difference between CP, KP and CVM?
- What is the headline figure of GDP used?
- How do I access data back to earlier years for GDP?
- What is the impact of Bank Holidays on GDP?
- Why do revisions occur?
- Is GDP measured the same across all countries?
- What is the difference between the preliminary estimate, second estimate and quarterly national accounts?
CP (Current Price)
Current price series (also known as nominal, cash or value series) are expressed in terms of the prices of the time period being estimated. In other words, they describe the actual price charged or paid for the goods or services at time of production or consumption.
KP (Constant Price)
Constant price series (also known as real terms) have the effects of inflation removed by fixing the prices of goods and services in one period (the base year), so that only the volumes change. In practice, the most common method for doing this is to divide the CP series through by an appropriate price index. The base year would normally be updated every five years or so to ensure that the product and industry mix of the economy is accurately represented. The UK national accounts published real terms series on this basis until 2003 when, in line with international regulation, they were replaced by annual chained volume measures.
CVM (Chained Volume Measures)
With chained volume measures, instead of updating the base year every five years, it is updated every year, meaning that, in practice, every series to be presented in real terms is estimated both in current prices and prices of the previous year (PYPs). The growth rates of the series in successive years on the same prices (for example 2006 estimated in current prices and 2007 in PYPs) are linked together in a chain of short series (known as chain-linking) to give a full real terms time series. CVMs are more responsive to major structural changes in the economy and, given the fact that the industry and product mixes of the economy are changing more rapidly now than in the past, they provide a more accurate picture of change in the economy than constant price series rebased every five years. All expenditure components of GDP are published on both CP and CVM bases; all output components on a CVM basis (annual production data are published in CP terms as well). Income components are only published in current price terms, as there is no meaningful means of producing operating surplus on a real terms basis. This is because, whereas for most transactions (for example purchases from a shop), there is a price element and a quantity element, this is not true in the case of profits for which there are no price or volume components. Within the sector accounts, the only data series published in real terms is real household disposable income (RHDI), everything else is in nominal terms.
The headline figure of GDP used is the growth in Gross Domestic Product at market prices - Chained Volume Measure. Latest figures are available from Key Economic Time Series Data.
Data back to earlier years can be found in the dataset associated with the release it was produced with. To access the dataset please follow these steps:
Open up the ONS homepage: www.ons.gov.uk
Select the "Data" tab
Scroll down the right hand section (Filter Results) and ensure only datasets box is ticked (un-tick reference tables)
Type the release you require for example 'Quarterly National Accounts' in "Search datasets"
Click on the latest dataset
Click on "Select series from this dataset"
Select the table you require for example "A2"
Then select the series you require, for example "ABMI: Gross Domestic Product: chained volume measures: Seasonally adjusted"
This will provide you with data for a longer period of time
Bank Holidays in the UK are not considered to be a special event or have a particular impact on the figures we release as these are holidays that occur every year. For a Bank Holiday to be considered a special event with potential impact it will usually happen only once, for example the royal wedding.
For more information visit the Special Events Calendar, this is what ONS will class as a Special Event and also describes the impact, or our guide to how we are developing a policy on Special Events (209.3 Kb Pdf) .
The National Accounts Revisions policy (41.7 Kb Pdf) explains why revisions occur.
The UK National Accounts including GDP are compiled using the European System of Accounts 1995 (ESA95) which itself is based on the System of National Accounts 1993 (SNA93). These systems are recognised worldwide and are adhered to by the majority of countries.
What is the difference between the preliminary estimate, second estimate and quarterly national accounts?
In the UK three different theoretical approaches are used in the estimation of one GDP estimate.
GDP from the output or production approach - GDP(O) measures the sum of the value added created through the production of goods and services within the economy (our production or output as an economy). This approach provides the first estimate of GDP and can be used to show how much different industries (for example, agriculture) contribute within the economy.
GDP from the income approach - GDP(I) measures the total income generated by the production of goods and services within the economy. The figures provided breakdown this income into, for example, income earned by companies (corporations), employees and the self employed.
GDP from the expenditure approach - GDP(E) measures the total expenditures on all finished goods and services produced within the economy.
The estimates are 'Gross' because the value of the capital assets actually worn away (the 'capital consumption') during the productive process has not been subtracted.
Estimates for GDP cover calendar years and quarters and the publication dates are available well in advance. Annual estimates are published in late summer as part of the UK National Accounts. Quarterly estimates are published more frequently and are updated with more information as it becomes available each month.
For example, GDP estimates for the first quarter of the year - Q1: January, February and March - will become available:
1st estimate: Preliminary estimate of GDP - based on information on output - published 3.5 weeks after the end of the quarter. Provides the first estimate of growth in GDP.
2nd estimate: Second estimate of GDP - based on information from all approaches - published eight weeks after the end of the quarter. Provides information on the level of GDP as well as the growth in GDP.
3rd estimate: Quarterly National Accounts - the full national accounts - published 12 weeks after the end of the quarter