The National Bureau of Statistics (NBS) said it would release two inflation readings for December after a methodological change led the headline rate to more than double.
This was disclosed during a virtual stakeholders engagement convened by the NBS and the Nigerian Economic Summit Group (NESG) on Monday.
The stats office explained that the expected spike in inflation is driven by technical base effects linked to the recent rebasing of the inflation series rather than changes in economic fundamentals.
According to the Statistician-General and chief executive of the NBS, Mr Adeyemi Adeniran, the inflation data due on Thursday, January 15 are projected to show an artificially spiked rate of 31.2 per cent last month, from 14.5 per cent in November. However, to provide transparency, the agency will take the unusual step of publishing both the headline rate that reflects economic fundamentals and the inflated figure.
Mr Adeniran explained that the projected December spike stems from the rebasing of the Consumer Price Index (CPI) which adopted 2024 as the new base year after a 15-year gap from the previous 2009 base.
He emphasised that base effects are a common feature of statistical practice, particularly in index-based measurements.
“Following the rebasing exercise and the methodology adopted for December 2025, a significant artificial spike in the inflation rate is expected, as some analysts have already projected. This spike arises from the base effect, with December 2024 equated to 100 following the rebasing.
“Base effects are common in statistical practice, particularly when comparing data across periods with unusually high or low prices. They are neither unexpected nor unusual.
“However, when such effects occur, especially when they are artificial and arithmetic rather than reflective of structural changes in the economy, it is essential to clearly communicate and explain them to users,” he stated.
“Transparency requires that we provide a clear picture of actual price changes rather than simply reporting an artificial spike that does not reflect economic realities. This is why we convened this meeting to inform our critical stakeholders and users of our data,” he added.