Statistics is not always the bedfellow of lies and damned lies. At its best, it brings epiphanies. An initiative by the OECD and the World Trade Organisation to map the value added embodied in international trade flows should be an eye-opener for policy makers.

Conventional export and import figures are calculated as the total value or volume of goods or services traded between two countries. But in a globalised supply chain, the elements making up a final product may cross national borders many times during the production process. Simple bilateral numbers do not capture this.

The researchers have painstakingly calculated the value a country adds to the goods and services it exports, by deducting the inputs going into their production that the exporter first had to import. Locating where the value in traded products is created and who reaps the rewards gives a truer picture of trading relationships.