Policies & Methodologies
In this area you will find links to downloadable PDF versions of the published policies and methodologies relating to the collection and publication of the UK Overseas Trade Statistics (OTS). Summary detail regarding the impact of the policies and methodology on the published OTS can be viewed in 'Understanding OTS data'.
Methodology paper for the Overseas Trade Statistics
This methodology paper covers all aspects of the Overseas Trade Statistics methodology – data sources, classifications and definitions, quality assurance, publications and governance. It is a useful companion to the trade data, providing the definitions and methodologies on which the data are based. The Overseas Trade Statistics Methodology paper (July 2016) is available here.(pdf)
General to Special Trade basis methodology change
From the May 2016 month of account our national trade-in-goods statistics have been compiled using the ‘Special Trade’ system. All such statistics prior to May 2016 were compiled using the ‘General Trade’ system. This switch in methodology is due to a change in legislation affecting the way in which goods are declared to Customs. For more details see the Overseas Trade Statistics Methodology paper (July 2016).
The special trade system is already used for the trade-in-goods statistics sent to the EU Commission. Historic data compiled under the special trade system can be found on the Eurostat website here: Eurostat - Comext Database.
Suppression of data
Some of the collected, detailed trade data is suppressed from publication to protect sensitive business and national interests. The policy applied to the OTS is available here:
June 2016: OTS Policy Statement: Policy on Suppressions (pdf)
Current suppressed codes can be found in the Related links area of this page.
Suppression of Exporter and Importer details
Some information on exporter and importer details is withheld in order to protect trader confidentiality. The suppression policies applied to each of the above can be found immediately below.
Revision of published data
OTS data are subject to scheduled revisions to provisional data (routine monthly updates) and non-scheduled revisions to final data (historic revisions) in accordance with the Code of Practice for Official Statistics and the HMRC policy on Revisions available here:
June 2013: HMRC Policy on Revisions to Data (pdf)
OTS EU data is collected via the Intrastat survey of trading businesses. An estimate is included in the published OTS on a monthly basis, to take account of trade yet to be declared.
February 2010: OTS Methodology: Enhancement of non-response estimation (pdf)
Net mass estimation methodology
From January 2010 an estimate of the quantity (net mass) will be published for those commodity codes where the Intrastat regulations do not require it to be collected from the EU trade declaration. Details of the estimation methodology are available here:
February 2010: Estimation of Net Mass Data from 1 January 2010 - Intrastat (Update) (pdf)
Regional Trade Statistics (RTS) methodology
RTS were introduced in 1999 to support the economic decision-making of the devolved Scottish Parliament, Assemblies and other regional bodies within the UK. These statistics provide a useful breakdown of the flows of imports and exports between regions of the UK and other countries. The collection and publication methodology for the RTS is available here:
September 2016: UK Regional Trade Statistics methodology (pdf)
From January 2014, Non-Monetary Gold will be included in OTS data series.This change will occur in the January 2014 data. The first release of data affected by these changes was published on 12 March at 09:30 and 18 March at 09:30 for Non-EU and EU respectively.
A summary of how this affects past data and the reasons why we are doing this are outlined in the documents below: