The National Bureau of Statistics (NBS) has projected a temporary “artificial spike” in Nigeria’s inflation rate for December 2025, attributing the expected increase to a reference period adjustment arising from the recent rebasing of the Consumer Price Index (CPI).
Gatekeepers News reports that the Statistician-General of the Federation, Adeyemi Adeniran, disclosed this on Monday during a stakeholder engagement on the December 2025 CPI and inflation, organised by the NBS in collaboration with the Nigerian Economic Summit Group (NESG).
According to Adeniran, the anticipated spike is the result of a base effect linked to December 2024, which has been equated to 100 following the rebasing exercise.
“This artificial spike is as a result of the base effect of December 2024, which is equated to 100, following the rebasing exercise,” he said.
He explained that base effects are a common statistical occurrence when comparing inflation data across periods, particularly when transitioning from unusually high or low price levels in the base period.
“It is important to state that the base effect is a common feature in statistical practice when comparing yearly or monthly data, especially if you are coming from high or low prices from a base period to the current period,” Adeniran said.
“It is not something unexpected, it is not something unusual. Base effect is common in statistical exercise.”
The statistician-general emphasised that the projected spike is purely arithmetic and does not indicate any structural deterioration in the Nigerian economy.
Providing further technical clarification, Ayo Anthony, director of prices and trade at the NBS, said the revised CPI basket now comprises 934 products, up from 700 previously, to better reflect changes in household consumption patterns over the past 15 years.
He said more than 400 new products were added to the basket, while about 200 items were removed because they are no longer widely consumed.
Anthony noted that linking the rebased CPI with the old index could temporarily distort the December inflation figures.
“If the CPI for December is projected at 131.2, derived from November’s 130.5, it does not represent the true state of the economy. This is why we apply normalisation to remove the base effect,” he said.
According to him, normalisation involves adjusting the index reference period to ensure comparability.
“If we don’t normalise, the year-on-year inflation in December will not be speaking to the true reality of the inflationary pressure of the economy,” Anthony added.
He assured stakeholders that the base effect would not affect inflation readings from January 2026 onward.
The NBS said Nigeria’s inflation figure for December 2025 will be officially released later this week.
Misleading Inflation Signals Could Undermine Reforms — NESG
In his opening remarks at the event, Tayo Aduloju, chief executive officer of the Nigerian Economic Summit Group (NESG), stressed that credible CPI data is critical as Nigeria transitions from economic stabilisation to consolidation.
He said accurate inflation statistics help anchor policy coordination, guide monetary and fiscal decisions, shape wage negotiations, and strengthen public confidence in economic institutions.
“In the consolidation phase, where we are transitioning to from a macro point of view, errors in policy can reverse hard-won gains,” Aduloju said.
“Misleading inflation signals can be very costly in this phase of macroeconomic reforms. Equally, the CPI statistics is a confidence-building mechanism.”
Aduloju added that transparent communication and methodological rigour in data production help reduce uncertainty, sustain reforms, attract long-term investment, and entrench macroeconomic stability.
“When data is produced with methodological rigour, disclosed transparently, and communicated clearly, it strengthens trust in institutions,” he said.
He further noted that properly interpreted CPI statistics enable policymakers and stakeholders to track structural economic changes and respond effectively.
