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Where does Nigeria's plans to revise their GDP leave our understanding of growth in Sub-Saharan Africa? Estimates suggest it could jump as much as Ghana's did a few years ago – 60%.

This week Tim Harford talks to Morten Jerven from the School for International Studies at Simon Fraser University in Canada, author of Poor Numbers: How We Are Misled by African Development Statistics and What to Do about It', about the impact on development of these GDP statistics.

(Image: Nigerian currency. Credit: Dan Kitwood/Getty Images)
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