In this paper, Antoine Brunet questions the OECD method in calculating contributions to GDP growth. He tries to show this method induces the users to seriously misjudge the contribution of external trade balance to GDP growth. He shows there is an alternative method, i.e. the AB method which is mathematically as correct as the OECD one. And this method is much more pertinent and allows the users to distinguish between two kinds of countries: on the one hand, the mercantilist countries and on the other hand, the non-mercantilist countries.Growth contribution, External trade balance, Borrowing, Growth strategy, Mercantilism.