Base jumping

By J.O'S., R.L.W. and A.C.M.

Nigeria has become Africa's largest economy

FIGURES published on April 6th put Nigeria's GDP at 80.2 trillion naira ($509 billion) in 2013, taking it above South Africa in the rankings of the continent's economies by size. Its number-one rank was the result of updating the reference or "base" year used to calculate real GDP, from 1990 to 2010. The old method of calculation gave too little weight to service industries, such as telecoms and motion-pictures, that have grown in importance. On the 2010 price base, GDP is 89% larger than it is on the old 1990 price base. The scale of the upgrade in part reflects the time that had elapsed before Nigeria's number-crunchers updated their picture of the economy. Other African countries have also had their numbers bumped up substantially when the base year was updated. But few waited quite as long as Nigeria to make the change.