7.1. Introduction. The present chapter builds on the discussion of the different data sources contained in IMTS 2010, chapter VIII, on data compilation strategies, and in chapters II to IV of this Manual. It describes challenges and good practices in the merging of customs and non-customs data, as well as of different pieces of information from the same source thereby linking the discussion on data sources (and the legal framework) as contained in part one of this Manual,with the discussion of data compilation as contained in part two. The scope of this chapter is limited to the compilation of international merchandise trade statistics. Its content is related to, but clearly different from that of chapter XI, which deals with the integration of trade and business statistics, aimed at generating additional and better information as well as efficiency gains in the compilation of economic statistics.
7.2. IMTS 2010 recommendations. IMTS 2010 recommends the use of customs records as the main and normally preferred data source, but recognizes that full coverage cannot be achieved through the use of custom records only, either because the relevant transactions are not or are no longer subject to customs controls or surveillance, or because record-keeping may not be adequate from a statistical point of view. It is recommended that, in such cases, customs-based data be supplemented with information obtained from other sources, as necessary, to ensure full coverage of international merchandise trade statistics. Further, it is recommended that non-customs sources be used as substitutes for available customs records only if they provide a cost-effective means of improving the quality of trade statistics (IMTS 2010, paras. 8.2 and 8.9).