Nigeria's official population (~220-230 million) may be significantly inflated and could be closer to 170-180 million[1]
This overcount is likely driven by political and financial incentives for states
I'm unsure of the implications if this is accurate
If states have uniformly inflated populations than the distribution of resources could still be divided evenly
Nigeria would still be the biggest country in Africa and companies/governments/NGOs would have similar cost benefit analysis for working and investing there
This is a very shallow investigation
Why did I bother looking into this?
The below text sparked an investigation into Nigeria's population claims. It was slightly hidden in the 4th section in one of Yaw’s excellent Substack posts.
Yaw went onto explain his reasoning for thinking the population was much lower than current estimates.
In a low trust society, in order to ensure loyalty, you must buy off elites - political patronage. Nigeria hasone of the lowest tax revenues as a proportion of its economic outputamong nations, even by Africa standards. Instead 65% of Nigeria’s government revenue is oil export proceeds. Then oil is distributed to provinces to “buy” them off. The oil revenue is distributed in proportion to the population of each province. This incentivizes a system where more money is concentrated in more populace regions. This incentivizes provinces to over report fertility rates, undercount child mortality rates, undercut emigration rates, over report population sizes, and not check population estimates accurately. Nigeria hasn’t done a census since 2006. Nigeria was supposed to do a census in 2023, but it was postponed. Even as of June 2024, the census has not been done yet.
To be honest, I wouldn’t be surprised if Nigeria’s population was closer to 170M.
My instant reaction was that this sounds potentially exaggerated or mistaken, surely you can't lose 50 million people without realising. And wouldn't there be incentives for the UN, other governments, companies to know how many people live in Nigeria. So I set about trying to find out if I'm wrong, and if the hours I spent learning the populations of different countries were even more pointless.
The National Population Commission data comes from a 423 page report that is partially based of the 2006 census with various metrics assumed to remain constant.
I then looked to see if other people had reported on this and saw a few articles that suggested there was a difference in actual and census populations.
...in Nigeria, last month’s national census was met with protests, boycotts, charges of fraud, and at least 15 deaths. Thousands of other enumerators walked off the job because they hadn’t been paid, and many people in large swaths of the country say they still haven’t been counted.
Passion and conflict are nothing new for Nigerian censuses. Their results decide the division of federal money and the balance of political power in a nation split almost evenly between a largely Muslim population in the North (which has traditionally controlled the government) and the coastal, more-urbanized, and largely Christian South, which regularly accuses northerners of rigging the census for political gain...[The North’s political strength arose initially from the results of the 1952-3 Census, which showed 54 percent of the country’s population resided in that area]
Bola Tinubu, the governor of Lagos state, called for a recount and said the census figures were false. Nigeria’s president Olusegun Obasanjo called those who dispute the results “confusionists,” adding that when they saw the census didn’t break the country, they sought to sow confusion...
Explaining his objection to the census results, Tinubu claimed that a parallel census conducted by Lagos in collaboration with the National Population Commission put the state’s population at more than 17.5 million, not 9.0 million, as the 2006 census suggested...
In a report on the 2006 census process, the chairman observes that even before the census was conducted, highly placed individuals and organizations in several states had already determined to the decimal point the population of a particular area or region. “Almost all these wild guesstimates apparently were based on their perceptions mostly out of ignorance or possibly ulterior motives to suit their agenda,” he notes.
And on the incentives behind the inflated numbers.
Census numbers in Nigeria guide political redistricting for each of the country’s 36 states, the distribution of federal funds, and even civil service hiring. However, historically, southerners tend to think resources are not distributed equitably. For instance, more than 90 percent of the country’s revenue comes from oil in the south, but the north controls about 55 percent of Nigeria’s revenue
I'd like to highlight a section in the article linked above, which would suggest that the census issues could start from the households themselves.
On the first page of the census form, there was enough room to list up to nine household members. Oddly enough, data collected from some states in the South showed all households reporting exactly nine people.
Its population, too, at an estimated 183 million, is the largest of any African country...There is just one snag: they are almost certainly wrong. Many of the figures about the country that are making the rounds are patently absurd, and few more so than the population statistics, for an obvious reason: allocations of revenue from the central government and voting power in the capital depend on population estimates, so every region has an incentive to bump up its own count.
...The first post-independence census in 1962 was already shamelessly rigged. An initial count suggested massive growth in eastern and western districts, which claimed that their population had increased by an average of 70% over the previous decade, compared with a 30% increase in the north. That would have shifted power from the northern elites who controlled the country, so they quickly scrapped the count and started again. This time, miraculously, the north’s population was found to have increased by 84% (an extra 9m people), just enough to ensure it had slightly more than half Nigeria’s population Almost every census since then has been disputed. One in 1991 was ditched when it seemed to show that the country’s total population was about 30% smaller than expected.
The latest one, conducted in 2006, put the total at 140m, a number that provides the basis for current estimates and forecasts. But some academics reckon that the population of some northern states was inflated by about a quarter, whereas that of some southern areas was trimmed in response to political pressure on the statisticians. The number of people in Lagos, the main southern commercial centre, was said to be just over 9m. That allowed northern rulers to claim that Kano, the main northern commercial centre, had more people and was thus entitled to more resources. Lagos officials subsequently did their own count and claimed 17m.
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.
It seems from the above posts, that there are plenty of incentives for each state to bump up population numbers.
Funding & resource allocation (mainly from oil money)
Political power
Civil service positions
Military positions
Potential Data Sources
I then started to look into other ways to see if the population projections were inaccurate.
National Identification Numbers
Nigeria has a national ID card run by the National Identity Management Commission, which can be registered from birth. The number of Nigerians with National Identification Numbers (NIN) rose to ~104 million by the end of 2023.
This is a 10.8% increase from the 94 million that was recorded as of the end of December 2022. This signifies that only 10.13 million Nigerians registered for NIN in 2023. A monthly average of enrolments reveals that 844,167 Nigerians got NIN per month in 2023.
This is a far cry from the Federal Government’s target of 2.5 million registrations per month.
I then looked into enrollment per state to see if there were any discrepancies (more enrollments than population or a large difference in registration between states). It looks like the smallest states have the lowest percentage enrolled but that could be plausible for harder to reach and poorer rural areas.
There is a reasonably large gap between Lagos and Kano in percentage registered, but that could be a cultural/economic difference. I'm not sure I can take anything conclusive away from this but it doesn't disprove a smaller population.
State
NIN Enrollments (millions)
Population (2023) (millions)
Registration Rate
Largest 5 States
Lagos
11.43
15.8
73%
Kano
9.19
16.3
57%
Kaduna
6.45
8.3
78%
Ogun
4.41
6.4
68%
Oyo
4.04
7.5
54%
Smallest 5 States
Taraba
1.49
4.3
34%
Cross-River
1.19
4.1
29%
Ekiti
1.03
3.4
30%
Ebonyi
0.84
4
21%
Bayelsa
0.66
2.4
28%
Tech usage
I then thought that it may be easier to track usage of online services that a high percentage of the country use. This may undercount younger, older and more rural populations, but may be relatively accurate as a lower bound for 16-65 year olds (although people could have multiple accounts).
It was hard to find accurate[2] data, none of the large companies, as far as I can tell, release usage data on a country level.
Sim Cards
Another path was to look for sim card usage, and recently there was a NIN-SIM verification exercise that would incentivise people without a NIN to get one so that they could keep on using their sim.
The recent National Identification Number (NIN)-SIM verification exercise has caused Nigerian mobile network operators to lose 64.3 million subscriptions, as the Nigerian Communications Commission (NCC) concluded the programme on September 14, 2024.
The verification, aimed at linking SIM cards with verified NINs to improve security and user accountability, saw major subscription losses across the nation’s top telecoms
Globacom’s active subscriptions dropping from 62.1 million in March to just 19.1 million
9mobile went from 11.6 million subscribers to only 3.6 million
MTN retained a lead with 78 million active subscriptions despite losing 3.7 million
Airtel ended the quarter with 53.7 million users, shedding about 9.6 million
The NIN-SIM verification mandate began in December 2020, with multiple extensions and deadlines given before the final September 14 cutoff. The delays led to chaos at telecom outlets, with customers scrambling to verify their NINs in time.
This suggests there are at least 154 million phone subscriptions, but then anecdotally people have multiple subscriptions (back to square one).
I personally own 4 lines. One obtained for personal reasons, held since 2003, two picked as corporate lines in the course of my career, the last embedded in my portable wifi device.
Both my parents have 3 each, several colleagues, friends and contacts have more than two lines.
I was on a call with representatives of a client on Jan 3rd and we took a quick poll on the subject. Two of them (like me) had four lines each and the third person with had two.
For several reasons, connectivity, business, it is very common for Nigerians to own more than one number.
UN Population Estimates and Projections
This is more tangential to current population, but the UN has revised their estimates for how large Nigeria will be over the years. I only picked a few years so can't confirm that it was smooth lines vs lots of ups and downs.
In the 1990's their current estimates were around 90-100 million. After the 2006 census which said there was 140 million people they increased their historical estimates and future projections. Although, at some point more recently, they have revised down their long term projections for 2100 from ~730 million to ~477 million. It may be a case that their pre-2006 census estimates were more accurate than using those figures.
All of the below are the UN's medium estimate.
The 1990[3] estimate of the population in 1985 was 92 million.
Our World in Data has a post on the accuracy of UN projections for global population with most projections differing from the latest estimates by just 1% to 2%. Although if the estimates are wrong, that wouldn't show up using this method.
I think given the variance in the projections for Nigeria, some, if not all, have to be quite inaccurate.
Global projections have been relatively accurate, but this isn’t true for every region We should not assume that because global projections have been reasonably accurate, projections for individual countries or regions have been equally so. This also applies to specific age groups.
Over- and under-estimates of particular populations canceled each other out, leading to a total figure that seemed more accurate than it was for individual groups. For example, an overestimate of the population in Asia could be partly canceled out by an underestimate in Europe.
In a paper published in Population Studies, the researcher Nico Keilman, studied the accuracy of UN population projections by looking at the errors of large regions, age groups, and specific estimates of fertility and mortality trends...
Another significant error for some regions – affecting mostly Africa, Asia, and Latin America – was inaccurate population estimates in the first place (in what we would call the “base year” when the time-series starts). Many countries in these regions had poor census records and national statistics on the size and structure of the population. If the population in the start year is wrong, the projected population could be very wrong, even if you make reasonable assumptions about changes in fertility and mortality trends.
Incentives for not caring
Nigeria and international organisations seem to have weak/negative incentives for having accurate data. One question I had throughout, is that if this undercount is even close to being true, why hasn't anyone spent more time/effort looking into this. Maybe at the census conferences this is the hot topic, but I didn't find much conversation online. Here are some potential reasons why the different groups are not incentivised to investigate.
Within Nigeria
State governments benefit from inflated numbers through increased federal allocations
The national government benefits from appearing larger on the global stage and supporting favourable states
Opposition parties want to challenge numbers, but only in regions where it benefits them politically
Academics and researchers might face political pressure not to investigate
International Organisations
The UN works with official government statistics and may be hesitant to challenge member states' data
Aid organisations might prefer higher numbers to justify larger programs
International organisations need to maintain working relationships with the government and don't have the capability to run a national census
The cost and complexity of conducting independent verification will outweigh the benefits
Development banks and funding agencies use official statistics for consistency
Private Sector
Companies care more about specific market metrics (purchasing power, consumer behaviour) than total population
Multinational corporations can adjust their internal projections without publicly challenging official figures
The difference between a subset of 170 and 220 million potential consumers might not change investment decisions significantly
Implications
I'm more persuaded that Nigeria's population is significantly overcounted. However, I'm still very uncertain about the implications of this, there aren't many areas where it is obvious that actions need to be changed given this update.
International Standing
Nigeria would remain Africa's largest country by population, ahead of Ethiopia (~120 million)
Its geopolitical importance would be largely unchanged
International organisations and businesses would continue viewing it as a key market
GDP
GDP per capita would increase by 15-25%
This could affect international development metrics and funding
Could change eligibility for certain development programs
Might affect terms of international loans
Development Indicators
Higher per capita metrics could improve Nigeria's standing in
Healthcare (doctors per capita)
Education (teachers per student)
Some indicators might worsen (it depends on whether you are measuring a positive or negative indicator, and the denominator gets decreased)
Child mortality rates if these numbers aren't similarly inflated
Malaria prevalence
Domestic Politics
Resource Allocation:
Federal revenue sharing between states could be significantly impacted
Alternatively, if all states are inflating their populations uniformly, existing allocation could be accurate and need minimal change
International Aid
Donor calculations might shift
Overall aid levels unlikely to change dramatically
Need still substantial
Political considerations often drive aid more than population
Future Research
Nigeria
I'm not a researcher, so it would be useful if someone has more time to spend looking into this. Here are some other areas that might be useful to dive into.
Import/export data
Interviews with people who have looked into this before
Population people (including the UN)
Some sceptics are also referenced in The Economist article
Satellite imagery
Housing data combined with sampling
Comparing to similarly wealthy countries with more accurate data
Migration data to countries with accurate statistics
Although this depends more on country relationships than size of the country
Vaccination coverage for verifiable vaccines (i.e. BCG)
Prediction markets
I'm sceptical as there isn't an easy way to verify what is true, if you made it based on the next census numbers, that could be (a) years away and (b) inaccurate
Other Countries
The UN population reports also include other countries[9] that haven't had a recent census, and population estimates could be widely off the mark. This is mainly because of conflicts but is sometimes politically motivated. If someone is interested it may be useful to investigate population numbers in these countries.
And the data I did find from marketing consultancies sometimes conflicted in the same paragraph.
WhatsApp: With over 95% of internet users aged 16-64 years, WhatsApp remains the leading social media platform in Nigeria. Its user base is estimated to be around 8.8 million.
Facebook is the second most popular platform, with a significant user base of over 36 million in 2022. This represents a user penetration rate of around 16.7%.
Unless someone from a large tech company wants to come forward with country usage stats and how that compares to the GDP/other metrics and expected usage given a country of that size and wealth, this is likely to be a dead end.
Whilst writing this up El Salvador released their 2024 census results (after a 17 year gap), with a population of 6.03 million, which was ~5% less than the 2024 UN projection of 6.324 million. They also had the bluest kick off census rally I've ever seen.
One thing which may be newly possible in the last few years is getting satellite imagery of the country and using AI to count houses. With appropriate methodology, this is far more likely to be accurate than relying on bureaucratic reporting and/or projections, although there are the obvious pitfalls and probably some non-obvious ones too in backing this out to population. I believe MSF used to do something like this for their deployment areas but I haven't heard of it attempted at a countrywide scale.
Small houses in a developing country may be occupied by between 0 and 20 people depending on abandonment, age profile and overcrowding (all of which tend to change more in the short term than construction), and that's before considering apartments. You might be able to pick up on a few concealed trends like the emergence of new townships in a region which notionally has unchanged population but the margin for error is probably bigger than the apparently huge margin for error in Nigeria's official population records.
To take the example from the OP: one of the major problems was a census permitting up to 9 people where some regions ended up with every household reporting nine people.Satellite data won't tell you which houses have claimed more residents than actually exist (or indeed which houses underreport residents because the number of households containing more than nine people won't be zero)
We use this for our healthcare mapping tool health AIM to accurately estimate the population in healthcare "black holes" where we launch health centers.
The problem is that house counts alone doesn't get you to an accurate population estimate. You need to know the number of people living in each house, which varies wildly between direct staff. We used to use a world bank estimate of 1.8 per hut or something in our area but that's far too loose to check population estimates.
An interesting method might be to check world pop's estimates over specific small sample sizes and then physically visit those places and see whether the online counts were consistently higher, lower or similar to the real life counts. I would imagine with a few hundred samples of 15-30 households that might get close to answering the question (can't be bothered doing the power calculation). Could probably do that for somewhere between 50k and 100k for what it's worth.
For what it's worth, AMF has population data from distributing bednets to every household. As an organization that cares about being highly effective, AMF tries hard to get the number of nets right. The target is to have approximately one net per 1.8 people (a net covers two people usually, but then there are households with an odd number of people or with pregnant women).
It looks like AMF's numbers are quite a bit higher, except in Bauchi state. This makes me slightly less willing to believe that Nigeria's population numbers are inflated. But of course, AMF could have been a victim of bad initial population estimates, or could have had left-over nets that were then given to routine distribution or used in other locations. I don't have any information about that.
Details vary by country. It's often a process where enumerators go door-to-door and interview the head of household to determine how many people live in a household. There can be some incentives to over-report the number of people, to receive more bednets. However, there is a limit on the number of nets per household (usually 3 or 4), and some of the data is independently verified by a second team of enumerators.
Is there reason to believe that Nigeria's population size is more likely to be exaggerated than other LMICs? (Since I imagine the incentives to exaggerate, and weak safeguards against this, exist in many other contexts too)
I have heard anecdotally that there is the opposite problem in Uganda and Burkina Faso.
In Burkina Faso the issue was that GDP per capita numbers were calculated from industrial output divided by population estimates so in order to look good, local government had an incentive to underestimate population so they seemed richer.
It's a particularly acute issue in federal and resource-rich countries in which such large relative amounts of cash are distributed according to local population numbers, so I'd imagine more exaggeration in Nigeria than the average LMIC.
Oliver Kim's How Much Should We Trust Developing Country GDP?, a review of Morten Jerven's 2013 book Poor Numbers: How We Are Misled by African Development Statistics and What to Do About It, makes the same point about GDP as well. Improving data collection in underresourced areas in general seems like a cross-cutting 'cause X'.
Some quotes:
Hollowed out by years of state neglect, African statistical agencies are now often unable to conduct basic survey and sampling work. Jerven writes:
In 2010, I returned to Zambia and found that the national accounts now were prepared by one man alone… Until very recently he had had one colleague, but that man was removed from the National Accounts Division to work on the 2010 population census. To make matters worse, lack of personnel in the section for industrial statistics and public finances meant that the only statistician left in the National Accounts Division was responsible for these data as well. (pg. x)
Without the staff to collect and analyze survey data, statistical agencies are usually forced to improvise, guessing the size of the economy from population figures, which are themselves extrapolated from censuses that are decades-old.
... I’m haunted by the words of the lone Zambian statistician, sitting in his empty office, who asks Jerven plaintively: “What happens if I disappear?”
Many African states are failing at the basic task of knowing how many people live in their borders—let alone accurately measuring their economic activity. The vast, unobserved informal sector (which includes subsistence farming, and something like 60% of working people) is usually estimated just as a direct function of population.5 Lacking direct harvest yields, estimates of agricultural output are often produced using FAO models based on planting-season rainfall data.6 Even the minimal task of measuring the goods traveling across borders—in theory, the easiest thing for a sovereign state to accomplish—is occasionally beyond the reach of statistical agencies. Until 2008, landlocked Uganda only collected trade data on goods that eventually passed through the Kenyan port of Mombasa, ignoring the four other countries on its borders.7
In the absence of good underlying data, the prevailing approach for GDP in developing Africa can be summarized as:
Income estimates… derived by multiplying up per capita averages of doubtful accuracy by population estimates equally subject to error. (p. 39)
Poor Numbers came out in 2013, attracting a wave of scholarly and policy attention (including by Bill Gates). Once you’ve heard its arguments, it’s virtually impossible to look at a GDP statistic the same way again.
But what actual progress has been made in the statistical capacity of nations?
Seemingly, not much. In late 2014, perhaps in response to Jerven’s book, the World Bank relaunched its website for its Statistical Capacity Indicator—a metric on a 0-100 scale which scores countries based on the strength of their “Methodology”, “Source Data”, and “Periodicity and Timeliness”. But even by this clunky internal metric, progress has been glacially slow: in 2004, the average score for African countries was 58.2; in 2019, it was just 61.4.
Moreover, over six years of an economics PhD, I have never heard of any economist using this statistic. Poor Numbers is well-cited and well-read (at least by Africa specialists), but its lessons about the fundamental unreliability of statistics have largely not been absorbed in how we actually do economics.
This is well-written, and your reasoning is sound. However, I remain skeptical about the possibility of a credible census in Nigeria. The political elites often require inflated figures for political gain, while the southeastern region of the country has historically been reluctant to participate or cooperate in the census process.
Very interesting! Thanks for digging into this and taking the time to write up what you found. I realize was definitely over-confident in the accuracy of population estimates!
AI Use Note: Main body text entirely human written. Claude (Opus 4.8) helped develop models of animal life histories in the appendix.
Cross-posted from Good Structures.
Executive Summary
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Summary
Back in November 2023 I posted here to launch Spiro and raise our first $198k. Two and a half years later this is an update and a fundraiser for the next step.
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One thing which may be newly possible in the last few years is getting satellite imagery of the country and using AI to count houses. With appropriate methodology, this is far more likely to be accurate than relying on bureaucratic reporting and/or projections, although there are the obvious pitfalls and probably some non-obvious ones too in backing this out to population. I believe MSF used to do something like this for their deployment areas but I haven't heard of it attempted at a countrywide scale.
Small houses in a developing country may be occupied by between 0 and 20 people depending on abandonment, age profile and overcrowding (all of which tend to change more in the short term than construction), and that's before considering apartments. You might be able to pick up on a few concealed trends like the emergence of new townships in a region which notionally has unchanged population but the margin for error is probably bigger than the apparently huge margin for error in Nigeria's official population records.
To take the example from the OP: one of the major problems was a census permitting up to 9 people where some regions ended up with every household reporting nine people.Satellite data won't tell you which houses have claimed more residents than actually exist (or indeed which houses underreport residents because the number of households containing more than nine people won't be zero)
Worldpop has taken this a step further and combined census population counts with house counts to estimate population.
https://www.worldpop.org/
We use this for our healthcare mapping tool health AIM to accurately estimate the population in healthcare "black holes" where we launch health centers.
https://health-aim.onedayhealth.cloud/login
The problem is that house counts alone doesn't get you to an accurate population estimate. You need to know the number of people living in each house, which varies wildly between direct staff. We used to use a world bank estimate of 1.8 per hut or something in our area but that's far too loose to check population estimates.
An interesting method might be to check world pop's estimates over specific small sample sizes and then physically visit those places and see whether the online counts were consistently higher, lower or similar to the real life counts. I would imagine with a few hundred samples of 15-30 households that might get close to answering the question (can't be bothered doing the power calculation). Could probably do that for somewhere between 50k and 100k for what it's worth.
Google has a great dataset that does exactly that: https://sites.research.google/gr/open-buildings/
It looks like they have even added building heights since I last checked!