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25.15.    Example from the United States of America. Metadata on the international merchandise trade statistics of the United States is made available online at the United States Bureau of the Census website in a Guide to Foreign Trade Statistics.[113]  This resource provides a detailed description of the United States Foreign Trade Statistical Program, and includes information on the legal framework (“Authority”), data sources, concepts and definitions (e.g., commodity classifications, coverage, valuation, quantity measurement, date of recording, etc.), data-processing procedures (e.g., seasonal adjustment, constant dollar adjustment), estimation methods for low-valued statistics, quality reporting (e.g., non-sampling errors, comparability issues, etc.), and data revision policies.  This metadata dissemination resource also includes contact information and other sources of information about the United States Foreign Trade Statistics Program. 



Box XXV.1

Towards the implementation of SDMX and DDI for IMTS: Experience of Mexico

The SDMX standard is designed for exchanging statistical data and metadata between two or more partners. Of particularly interest is the fact that inMexico, which is a federal country, SDMX can support both a national information sharing system and its links to other information sharing systems at the international level.  Following the decision to adopt the SDMX standard, theMexico’s National Institute of Statistics and Geography (INEGI) started developing the infrastructure required to make data and structural metadata available through web services. Tools developed by Eurostat as well as the support of OECD have been of great help in the accomplishment of this task.

The data (and related metadata) for a given statistical domain are structured in SDMX according to a Data structure definition (DSD), which describes the structure of a particular statistical data flow through a list of dimensions and a list of attributes (and their associated codes). 

Mexicois working on the adoption of SDMX technology in statistical projects in various statistical domains.  However, in January 2011, INEGI decided, in partnership with OECD’s Statistics Directorate, to give priority to the conversion of the “annual trade by commodity” data flow to SDMX. By the beginning of 2012, this data flow was released by INEGI for testing purposes in a web service, and it is expected that feedback will be received from OECD. The data structure definition for this data flow will include dimensions such as frequency, reference country, trade flow (exports, imports, etc.), commodity code (from the HS2007 classification), valuation (in FOB or CIF terms), partner country or region, and reference period.  It will include attributes like unit of measurement and observation status.

The issue of metadata is also covered inMexicothrough the implementation of the Data Documentation Initiative (DDI) as a fundamental tool for the integration of metadata for international merchandise trade statistics. The project is carried out with the support and advice of the World Bank. The policy of INEGI is to use both standards as linchpins for the metadata of the national statistical projects, thus strengthening the national system of statistical and geographical information.


[113] See