Inflation Adjusted HMRC Regional Trade Statistics for Scotland: Methodology

RTS is a valuable source of data, but does not provide estimates which directly cohere to the main Scottish Government trade statistics produced in ESS or the national accounts. Differences include the regional allocation methodology, the geographical extent of the data (i.e. that RTS does partly include exports from the continental shelf, whereas other statistics are ITL1 onshore only), and differences between what is counted as trade in either merchandise trade statistics (physical movement of goods) and statistics on a balance of payments basis (change of ownership).

For information on the comparability within the data across time and regions, users are advised to consult the Regional trade in goods statistics methodology note (HMRC). Most notably there has been a break in the time series from the start of 2021 for exports and from the start of 2022 for imports. Since these respective dates, statistics have been compiled directly from customs export declarations rather than the Intrastat survey for trade between Great Britain and the EU.

The customs declaration requirements are more complex than the single monthly aggregated Intrastat return and can result in differences between dates of declaration and actual movement of the goods out of the country. The Office for National Statistics has released an article explaining the impact of trade in goods data collection changes in more detail.

The ONS also produces estimates of Chained Volume Measures for the UK. Although the data for goods in the ONS estimates also comes primarily from HMRC, the ONS processes this data differently, including coercing it to match with the definition of balance of payments statistics from the International Monetary Fund (IMF). This involves changes to certain transactions, including adjustments to transactions which are not reported to HMRC. Other differences in methodology and data sources will also impact on comparability and coherence. A comparison with the ONS data is part of the planned development for this report.