Even allowing for all these swings and roundabouts, some researchers, using sophisticated satellite imagery and geographical information systems, reckon that the 2006 census considerably overstated Nigeria’s urban population, mainly in the north but also in some southern cities. That means Nigeria’s current population may be closer to 160m than 180m. The forecasts suggesting that Nigeria’s population will overtake America’s within a few decades are probably also wrong because they are based on high fertility rates observed in the past, whereas newer data suggest those rates are falling fast, especially in the south.The Economist does not cite its sources for "some researchers," but I'm guessing that the information comes from AfricaCheck:
Based on the Africapolis urban study, it appears to be more likely than not that Nigeria’s population today is lower than commonly cited. And the Organization for Economic Cooperation and Development (OECD), for one, has taken this into account in its estimates. “The OECD has adjusted Nigeria’s population figures on the basis of the much reduced urban populations estimated by the Africapolis team,” Dr Potts [Dr Deborah Potts, a reader in human geography at Kings College London] said. “Their calculations put Nigeria’s population at 110.1 million in 2000, compared to a UN estimate for that year of 123.7 million.” In a report, the organisation estimated that Nigeria’s population in 2006 was just over 134 million; below the 140 million reported in the census.Interestingly enough, the Economist laments this lower number since it suggests a smaller consumer market than people in business might otherwise be counting on. I think, however, that most of us are likely to agree that given the poverty and corruption in Nigeria--despite its vast natural resources--fewer people now and in the future is better than more.