Development Goals

Mental health problems in women during pregnancy and after childbirth and their adverse consequences for child health and development have received sustained detailed attention in high-income countries. In contrast, evidence has only been generated more recently in resource-constrained settings. In June 2007 the United Nations Population Fund, the World Health Organization, the Key Centre for Women's Health in Society, a WHO Collaborating Centre for Women's Health and the Research and Training Centre for Community Development in Vietnam convened the first international expert meeting on maternal mental health and child health and development in resource-constrained settings. It aimed to appraise the evidence about the nature, prevalence and risks for common perinatal mental disorders in women; the consequences of these for child health and development and ameliorative strategies in these contexts. The substantial disparity in rates of perinatal mental disorders between women living in high- and low-income settings, suggests social rather than biological determinants. Risks in resource-constrained contexts include: poverty; crowded living situations; limited reproductive autonomy; unintended pregnancy; lack of empathy from the intimate partner; rigid gender stereotypes about responsibility for household work and infant care; family violence; poor physical health and discrimination. Development is adversely affected if infants lack day-to-day interactions with a caregiver who can interpret their cues, and respond effectively. Women with compromised mental health are less able to provide sensitive, responsive infant care. In resource-constrained settings infants whose mothers are depressed are less likely to thrive and to receive optimal care than those whose mothers are well. The meeting outcome is the Hanoi Expert Statement (Additional file 1). It argues that the Millennium Development Goals to improve maternal health, reduce child mortality, promote gender equality and empower women, achieve universal primary education and eradicate extreme poverty and hunger cannot be attained without a specific focus on women's mental health. It was co-signed by the international expert group; relevant WHO and UNFPA departmental representatives and international authorities. They concur that social rather than medical responses are required. Improvements in maternal mental health require a cross-sectoral response addressing poverty reduction, women's rights, social protection, violence prevention, education and gender in addition to health.

The contents of this report constitute technical advice provided by the staff of the International Monetary Fund (IMF) to the authorities of Nigeria (the "CD recipient") in response to their request for capacity development. This report (in whole or in part) or summaries thereof may be disclosed by the IMF to IMF Executive Directors and members of their staff, as well as to other agencies or instrumentalities of the CD recipient, and upon their request, to World Bank staff and other capacity development providers and donors with legitimate interest, unless the CD recipient specifically objects to such disclosure (see Operational Guidelines for the Dissemination of Capacity Development Informationhttp://www.imf.org/external/np/pp/eng/2013/061013.pdf). Disclosure of this report (in whole or in part) or summaries thereof to parties outside the IMF other than agencies or instrumentalities of the CD recipient, World Bank staff, other capacity development providers and donors with legitimate interest shall require the explicit consent of the CD recipient and the IMF's Fiscal Affairs Department. • Education-increasing access and improving quality. The relatively low resources devoted to education are insufficient to deliver quality education for all. With 50 percent of the population in school-age, we estimate that total annual spending in education would need to increase by 7.7 percentage points of GDP by 2030. A pragmatic approach should be taken depending on resource availability. For example, expanding enrollment could be done at a more modest cost of some 1 percentage points of GDP.

This technical mission was financed by the European Union under the EU-IMF Public Financial Management Partnership
• Health-tackling inefficiencies. Nigeria should deliver better outcomes at its current level of spending. Rebalancing the system, with an emphasis on primary care with public support, is critical. In the medium-term, additional annual spending of 4 percentage points of GDP would be needed to expand health workers, improve infrastructure, and improve health outcomes.
• Electricity-rehabilitating and expanding power infrastructure. Annual investments of 1 percent of GDP are needed to expand electricity access and keep up with population growth. Rehabilitating the existing capacity can help meeting part of these investments. Mini-grids can play an important role in mobilizing capacity to remote and vulnerable communities.
• Roads-expanding the road network. Increasing access roads from 26 to 75 percent of the rural population will cost 2 percent of annual GDP. It is critical to outline the road network and identify projects with high economic and social returns. The private sector can play an important role in this sector, supported by strong oversight to ensure value for money.
• Water and sanitation-picking low-hanging fruit. A priority is improving access for the most vulnerable. Ending open defecation and expanding basic water and sanitation can be achieved at a modest annual cost of 0.6 percent of GDP. In the medium-term, providing safely managed water and sanitation for all will cost an additional 2.5 percent of annual GDP.
Beyond resources, improving coordination and strengthening governance is critical to delivering on the SDGs. The federal administration through its Office of the Senior Special Assistant to the President on Sustainable Development Goals (OSSAP-SDGs) is committed to advance towards the 2030 goals. In line with policy options outlined by the World Bank and the United Nations, progress in these sectors requires a whole-of-government approach, supported by strong coordination between the federal, state, and local administrations. While development partners and the private sector can help, the government should be in the driving seat of these efforts. To support decision-making based on evidence, one priority is to collect and analyze data to inform best practices and better target scarce resources.

5.
Nigeria has shown gradual improvements in education. The share of literate adults increased from 55 percent in 2003 to 62 percent in 2018 (Figure 1.a). In the same period, increases in enrollment raised the average number of years of schooling by 2 years (Figure 1.b). To boost outcomes, the authorities launched in 2018 a strategic four-year plan, which focuses on improving access and quality. 3

6.
The education system is falling short. Like many other low-income and developing countries, Nigeria faces the challenge of educating large numbers of children in relation to the population. 4 Today, over half of the population is of school-age, compared to 36 percent in emerging economies and 25 percent in the advanced economies (Figure 2.a). Nigeria is failing this demographic challenge. Half of the school-age population (Figure 2.b) -nearly 50 million Nigerian children and youth-are not receiving any formal education.

7.
Furthermore, the education system seems to deliver poor quality to those enrolled. Nigeria ranks low in quality measures among low-income countries. For example, only 20 percent of pupils that complete primary school can read a three-sentence passage fluently or with little help, compared with 50 percent in Ghana and 80 percent Rwanda and Tanzania.

8.
The lack of funding explains part of these deficiencies. While other factors-security, distrusts in government, access to other basic services-hinder outcomes, the resources devoted to education seem insufficient to deliver universal and high-quality education. At 1.6 percent of GDP, the combined spending on education by the public and private sectors is relatively low (Figure 3.a). School infrastructure is inadequate, and teachers lack materials. Most math and language teachers fail to achieve 80 percent in tests aimed at ten-year-old pupils. 8 Overall, Nigeria's score in the index used to measure education SDG performance falls far below the median for low-income and developing economies (Figure 3.b).

9.
To address these challenges and make meaningful progress toward SDG4, Nigeria would need substantial additional resources. To match the strong performers among Nigeria's peers, we estimate that total spending in education would need to increase by 7.7 percentage points of GDP by 2030 (Table 1). This reflects the need to boost enrollment, increase the share of capital in total spending, reduce class size, and raise teacher wages.
• Increasing enrollment rates and improving infrastructure. Nigeria could aim at raising enrollment to 80 percent of the school-age population by 2030, i.e., universal coverage for two years of pre-primary, full primary and secondary education, and two years of tertiary education. 9 To cope with higher enrollment-and refurbish current facilities-a larger share of the increase in education spending would need to be directed to infrastructure.
• Increasing the quantity and quality of teachers. While Nigeria has smaller class sizes than LIDC, we find that further reductions would be needed to match the student per teacher ratio of 16.5 in good performing countries today. This is particularly important in public schools which today have an average of 33 students per teacher. In addition, to attract more qualified teachers, the compensation of teachers would have to increase at a pace faster than GDP.

10.
A gradual and strategic approach should be considered given the relatively large additional spending. One priority is to increase enrollment rates. We estimate that, assuming the current level of spending per student, this increase in enrollment would require additional spending of 1 percentage points of GDP ( Figure 4). This policy could be accompanied by larger commitments to school infrastructure, which would demand an additional 0.7 percentage points of GDP in spending. Smaller class sizes would require an additional 2.3 percentage points of GDP. 9 We assume full enrollment in 2030 for at least two years of preprimary and tertiary education and 12 years of primary and secondary education. I.e., the target enrollment rates are 50 percent for preprimary and tertiary, and 100 percent for primary and secondary. Overall, the targeted enrollment rate is 80 percent (16 years/20 years). Finally, higher wages to attract qualified teachers, would require an additional 3.9 percentage points of GDP.

Figure 4. Decomposition of Additional Spending in Education for SDG4
Source: IMF staff calculations.

11.
Beyond resources, it is critical to address disparities across genders, regions and public and private services. An equitable education system has positive effects on economic growth, helps alleviate poverty, and improve income distribution in the medium term. 10 • Disparities remain between the education received by girls and boys. 11 By ensuring equal educational opportunities to all children, regardless of gender, Nigeria could boost economic growth. For example, increasing the share of women with secondary education by one percentage point will boost annual per capita growth by 0.3 percentage points. 12 • Geographical disparities in outcomes are significant, driven by various factors, including security, economic barriers and low trust in formal education in some areas, especially for girls. 13 While 78 percent of Southwest children can read part or whole sentences, only 17 percent of Northeast children are able to do so. 14 Addressing these gaps in access is critical for economic growth-for every nine children, five live in the North.
• Disparities between public and private schools have been documented in terms of class size, teacher's quality, adequacy of facilities, curriculum practices, stability of academic activities. 15 13 UNICEF Education Program in Nigeria. Narrowing these gaps, particularly in primary and secondary education, could improve opportunities for the most vulnerable. In the medium-term, addressing these inequities would also help reducing the relatively high level of private spending in education.

12.
Nigeria made progress on its information system, but more efforts are needed. Detailed information on the number of students, teachers, and schools is available, but little is known about the spending on education by the different government levels or the private expenditure on education. 16 Much less is known at the school level. To support decision-making based on evidence, one priority is to collect spending data linking it to the provision of education services. For example, includes spending per capita and outcomes by region would help to inform best practices and better target scarce resources.

13.
Nigeria has made some strides in health outcomes yet lags far behind peers. Mortality rates of children under five years old dropped from 211 to 120 deaths per 1,000 live births in 1990-2018, a 60 percent reduction ( Figure 5.a). Progress has also been made in maternal mortality, which declined by 24 percent from 1990 to 2018. Yet, health outcomes lag those in countries with comparable per capita income ( Figure 5.b). Across indicators, Nigeria fares poorly. Infant mortality is the third highest in the world, far higher than countries with lower income per capita. Healthy life expectancy is just 49 years, placing Nigeria among the bottom six countries in the world. With a disproportionate share of out-of-pocket health expendituresabout 70 percent of the health expenditures-most households are financially vulnerable to health shocks. The World Health Organization ranks Nigeria's healthcare system at 187 among 190 countries. 17

14.
Health care spending is inefficient. Overall, Nigeria's score in the index used to measure health SDG performance falls far below the median for low-income economies ( Figure 6.a). 18 This low performance, however, does not seem to be explained by the level of spending. At 4 percent, the share of the GDP devoted to health in Nigeria is shy of that in India, Ghana, and Cameroon-countries with substantially better outcomes-albeit lower than the median for low income and developing countries ( Figure 6.b). In Purchased Power Parity dollars, Nigeria spends more on health per person than other low-income economies (Figure 6.c). At this level of spending per capita, Nigeria could achieve substantially better outcomes. In many 16 World Bank Group, 2015, "Nigeria Partnership for Education Project". World Bank.

15.
Addressing inefficiencies while increasing spending would be needed to make significant progress in the health SDGs. Under the current resource envelope, addressing inefficiencies should remain a priority-Nigeria should be delivering outcomes commensurate to its current level of spending. Nevertheless, in the medium-term, we estimate that more resources would be needed, including raising the share of health care workers in the population. We estimate to replicate the input/output mix in the good performers among peer countries today, Nigeria would need to increase health expenditure by 4.3 percentage points of GDP between now and 2030 (Table 2).
• Raising the number of health workers. To reach the standards of well performing countries, the number of doctors per 1,000 population needs to increase from 0.2 to 0.4 while the number of other health personnel per 1,000 population needs to increase from 2 to 4.
• Making wages more competitive. At 6 times GDP per capita, doctors' wages are low in GDP per capita terms relative to strong performers. There is scope to raise wages in the health sector at a faster pace than GDP growth, albeit gradually. This could contribute in reducing pressures for Nigerian doctors to migrate abroad. 19

16.
A rebalancing of the system, with the government playing a larger role in financing primary care seems necessary. The combined spending in health by the government (federal, state, and local) is just 0.6 percent of GDP. Over 85 percent of total health expenditures come from the private sector, of which the majority corresponds to out-of-pocket payments from 19 Since 2005, 18,949 doctors (43 percent of the doctors in 2018) have applied for a verification of standing letter (i.e., a proxy of migration). households. 20 This stands in contrast to the strong performing countries, whose median private share in health spending is 48 percent. The reliance on payments at the point of service is a high barrier to access health care for many and leads to more expensive care for both the patient and the system. 21 Catastrophic health events result in substantial loss of income for many families, with an additional 3.5 percent of the population falling into poverty every year. 22 This suggests ample scope for government interventions geared at expanding affordable access to health care for the most vulnerable. A starting point could be to strengthen the primary health care network, which can be effective in improving health care outcomes. 23 The government had set a mediumterm plan to reduce the financial barriers to accessing the healthcare system. 24

17.
Plans toward a universal health care insurance seem promising, but more political commitment is needed. Nigeria's insurance system is available only for formal workers. 25 Steps to expand access to insurance have been taken in the past few years. The National Health Act of 2014 established the legal framework for the creation and functioning of the Basic Health Care Provision Fund, which aims at providing financing for the most vulnerable to access to basic care. 26 However, more political and budgetary commitments are needed-the resources allocated to the fund thus far have been minimal.

18.
Beyond financing, weaknesses in governance and financial management could be addressed. Responsibilities for health care are shared across all layers of government-about one-third of public spending is carried by subnational governments. This allows for the localities to attend their constituencies in a direct way. The shared responsibilities, however, raise the need for coordination to prevent inefficiencies in the use of government resources and attend regional disparities. And the large footprint of the private sector in health care means that coordination should go beyond government resources. The adoption of the SDGs in national development plans provides an enormous opportunity for greater coordinating in public and private efforts in improving the health outcomes of Nigerians. Beyond a few programs and interventions that cross across governments, a global approach is needed in linking the overall health strategy with the total resource envelope available for health care.

III. PHYSICAL CAPITAL
A. Electricity

19.
The share of the population with electricity access increased from 40 percent in 2015 to 54 percent in 2020. 27 During the same period, the installed available generation capacity connected to the grid increased from 4,000MW to 7,500MW, the nominal transmission capacity increased from 5,000MW to 8,000MW, and the dispatch capacity increased from 3,500MW to 5,500MW. 28 The Nigerian Rural Electrification Agency (REA)-tasked with electrification of rural and unserved communities-connected about 100,000 households, impacting 500,000 people and providing more than 5,000 jobs. 29 In 2019, the number of total system collapse was reduced to 10, down from an average of 15 per year in 2010-18. 30

20.
Nigeria's electricity consumption amounts to about half of what would be expected at its current level of GDP per capita. The electricity supply chain-generation, transmission, and distribution-faces substantial challenges due to years of underinvestment. Only 7,500MW of the 13,500MW on-grid installed generation capacity is functional. Transmission is the system's bottleneck, dispatching 50 percent below its nominal capacity-less than 4,000MW is end-to-end operational through the grid. Of this, about 10 percent of on-grid electricity demand is unmet. Deficient on-grid supply forces consumers into costly off-grid alternatives, which account for 52 percent of electricity consumption. 31 Accounting for on-and off-grid provision, the electricity consumption per capita of 348kWh is below peers (Figures 7 and 8).

21.
Large investments are needed in the power sector to increase access and keep up with population growth. Between 2018 and 2030, the population is projected to increase from 196 to 263 million. In this period, GDP per capita in U.S. dollars is projected to increase marginally. Electricity consumption per capita is estimated to grow from 348 kWh in 2019 to 635 kWh by 2030 driven by increased access (Figure 9). To expand installed capacity by 22.4GW, at a unit cost of US$2,184 per kW (including generation, transmission, and distribution costs), Nigeria will have to invest an aggregate of US$49 billion in 2020-30, which on an annual basis is equivalent to 1 percent of GDP, including replacement costs (Table 3). 33

22.
In the short term, efforts to rehabilitate and upgrade generation and transmission capacity should be a priority. The Transmission Company of Nigeria is aiming at stabilizing the grid, coordinating procurement and investment, and closing the gap between demand and supply. The Federal Government of Nigeria and Siemens recently signed an implementation agreement for the Nigeria Electrification Roadmap. 34 As a first step, rehabilitating the existing infrastructure can boost end-to-end capacity to 7,000 MW. Solving network bottlenecks will enable full use of existing generation and distribution capacities, bringing the systems operational capacity to 11,000 MW. Finally, the plan includes upgrades and expansions in generation, transmission, and distribution to 25,000 MW. Rehabilitating and upgrading the existing capacity could be a cost-efficient way of meeting part of the required investment to meet electricity demand.

23.
The Sustainable Energy for All (SE4ALL) program envisions the increase in renewable sources in the energy mix. Nigeria is among the top 50 CO2 emitters. 35 The government plans to increase capacity in a more sustainable way. The SE4ALL program encompasses the Vision 30-30-30-i.e., boosting capacity to over 30GW with a share from renewable sources of 30 percent by 2030 (Table 4). 36

24.
Mini-grids can play an important complementary role. Nigeria presents excellent conditions for sustainable solar energy generation. Mini-grid sustainable solutions can complement the capacity supply in the lack of on-grid provision. Mini-grids can quickly mobilize scalable capacity and provide electricity to remote and vulnerable communities. The Rural Electrification Agency (REA) is defining the terms and standards for 250 new mini-grids in the country, while the World Bank and the European Union provide financing to its development. 37

25.
Reforming the electricity sector can have a large impact on equitable access. Increasing affordable electricity access can have positive effects on the most vulnerable. Off-grid electricity provision comes at cost to final consumers. For example, low-income households regularly dedicate 9 percent of their expenditures to energy (e.g., charging cell phones in kiosks with a kerosene generator for a fee). 38 Also, a significant share of income is spent by off-grid households on candles and fuel lamps. 34 See: https://press.siemens.com/global/en/pressrelease/siemens-and-nigerian-government-signedimplementation-agreement-electrification.

Table 4. Current and Target On-Grid Capacity Mix
Source: IMF staff calculations using the "Sustainable Energy for All Action Agenda (SE4ALL-AA)" (2016), National Council on Power, Federal Republic of Nigeria. Note: The cost of installed capacity per MW is calculated as the weighted average by type of source. The cost of generation and distribution is assumed to be 50 percent of generation cost each.

26.
The current administration has made significant investment in road infrastructure; nonetheless, a large proportion of Nigeria's 195,000 road network is in unsatisfactory condition due to insufficient maintenance. 39 The World Bank estimates that about 16 percent of the roads are federal, 16 percent of state, and 68 percent of rural. 40 While no reliable government assessment of the road network quality is available, the condition of many roads seems deficient (Figure 10). 41

27.
Only 26 percent of Nigeria's rural population have access to all-weather roads within two kilometers (Figure 11). Nigeria's road density is low in comparison to other countries. Nigeria's 22 km per 100 square km is below India (208 km per 100 square km), a country with a similar per capita GDP. Southern states have relatively higher accessibility than the Northern states. In 2014, the Rural Access Index (RAI) of Imo State was significantly higher (50 percent) than Adamawa State (

28.
Nigeria will have to invest a significant share of its GDP to improve road access. While construction costs vary by type (i.e., number of lanes and type of surface) and region, we estimate an average cost per kilometer of about US$550 thousand. Thus, extending the road network by nearly 180 thousand kilometers will require an aggregate investment of almost US$100 billion over 2020-30, which on an annual basis is equivalent to 2 percent of GDP, including depreciation ( Figure 12 and Table 5). Furthermore, we estimate that, on top of the 2 percent of GDP per year on new road infrastructure, Nigeria will have to invest at least up to 0.5 percent of GDP per year in refurbishing and modernizing its existing road infrastructure.

29.
The institutional governance of the road network could be strengthened. Crossing competences between government levels (i.e., federal, state, and local administrations) and functional competences within administrations (i.e., ministries, department, and agencies) impose coordination challenges. • Partnerships with the private sector need scrutiny to ensure value for money. The government is championing solutions with the private sector as a key player in the development of road infrastructure. While these partnerships can encourage private funding, without a strong institutional regulatory setup they may exacerbate governance problems. For example, roadfor-taxes programs could be used to bypass budgetary scrutiny.
• Scope for greater coordination. Road construction has been largely driven by ad-hoc programs with little prioritization. Appropriations for road construction lack funding, resulting in unfinished works and poor maintenance. At minimum, the federal government could take the leadership in outlining a national network with consideration of increasing maintenance of existing road assets as well as enhancing monitoring and accountability of ongoing projects.

30.
Nigeria has made some recent progress in water and sanitation provision. Water and sanitation indicators worsened in the 1990s and 2000s, reflecting years of poor maintenance and low investments in water and sanitation assets. 43 Partly because of this neglect, the current federal administration declared a state of emergency in water and sanitation. The gradient of progress has been noticeable. Between 2010 and 2018, access to basic sanitation increased from 32 to 42 percent of the population, an achievement given the rapid population growth. In the same period, access to basic water increased from 79 to 87 percent of the urban population and from 46 to 60 percent of the rural population.

31.
Yet substantial challenges remain. 47 million people still practice open defection. A third of the population do not have access to basic water services. Access to basic and safely managed sanitation services is even lower (Figures 13). Only 3.7 percent have access to safely managed water services (Figures 14). These deficiencies are higher in rural than urban areas, with disparities across regions and wealth quintiles ( Figure 15). 44 For example, access to basic water and sanitation is above 50 percent of the population in Anambra and Imo and below 10 percent of the population in Borno and Ebonyi. The federal government is making efforts to coordinate programs effectively and co-share expenses with the states through targeted programs.

32.
The government is prioritizing efforts and setting achievable goals. The authorities are committed to end open defecation by 2025. 45 The campaign "Clean Nigeria: Use the Toilet" launched in 2019 is based on dissemination of technical instructions for the construction of toilets and behavioral nudging aimed at sensitizing the population and mobilizing public and private resources. The program identifies the location, resources needed (US$2.7 billion), and responsibility (75 percent households, 25 percent government and PPPs) for the construction of 20 million toilets (Table 6). Following WHO recommendations, the government is taking a gradual approach to close the gap by reducing the distance to basic water and sanitation services from 30 to 15 minutes roundtrip. 46

33.
Nigeria can achieve high-impact basic coverage of water and sanitation at a moderate cost. We estimate the cost to provide universal safely managed access to water and sanitation following the World Bank's methodology. 47 Overall, meeting basic water and sanitation needs will require an aggregate of US$23 billion over 2020-30, i.e., only 0.55 percent of annual GDP including depreciation (Table 7). 48 Providing safely-managed water and sanitation will require an additional 2.5 percent of annual GDP, including depreciation.

34.
Making substantial progress in the water and sanitation SDG can have a positive impact on equity. The World Bank estimates that annual losses from poor sanitation-access

35.
Beyond mobilizing financial resources, institutional and technical capacity constraints need to be addressed. 50 The amount of resources and skilled labor required to address the construction of toilets, pipes, and facilities are large. On the other hand, these needs are likely to create business and employment opportunities, particularly in rural areas, attracting capital and skilled labor.  Hutton and Varughese (2016) and accounts for GDP growth and depreciation. Rural and urban cost per capita are assumed to be similar for basic services, and urban cost per capita are assumed to be three times larger than in rural areas for safely-managed services. Depreciation rate is assumed to be the inverse of seven years for basic toilets, 12 years for basic services, and 15 years for safely-managed services. 49 Water and Sanitation Program, 2012. Economic Impacts of Poor Sanitation in Africa. 50 Akpabio, E. M., 2012, Water supply and sanitation services sector in Nigeria: the policy trend and practice constraints (No. 96). ZEF Working Paper Series.

Appendix I. Education
The SDG costing estimate for education is expressed as the additional spending needed to perform well in the education SDG, that is, the difference between the spending needed in 2030 and the spending level today. Both today's education expenditures (as a percent of GDP), E 2018 , and the levels needed by 2030, E 2030 , are expressed as an identity: where w refers to teachers' annual wages as a ratio to GDP per capita, STR is the student teacher ratio, e signifies the enrollment rate, i.e. the number of students as a percentage of the studentage population, SAP indicates the student-age population as a percent of total population, and E oth , pertains to all education spending besides the teacher wage bill as a percent of total expenditures in education.
The spending needed in 2030 to perform well in the education SDG is the level of expenditures Nigeria would incur by 2030 due to projected demographics (student-age population) and if it matched, by 2030, today's levels of the education cost-drivers of the high performers among Nigeria's peers. These cost drivers include teachers' wages, the student-teacher ratio, the enrollment rate, and education spending other than the teacher wage bill. The approach of matching Nigeria's 2030 cost drivers to today's level of the high performers is seen in the corresponding columns of Table 2.

Appendix II. Health Care
The SDG costing estimate for health is expressed, analogous to that for education, as the additional spending needed to perform well in the health SDG, that is, the difference between the spending needed in 2030 and the spending level today.
Both today's health expenditures (as a percent of GDP), E 2018 , and the levels needed by 2030, E 2030 , are expressed as an identity: = 10 + 0.5 100 − ℎ where w refers to doctors' annual wages as a ratio to GDP per capita, D and M are the numbers of doctors and other medical personnel, respectively, per 1,000 population, and E oth pertains to all spending besides the health workers' wage bill as a percent of total expenditures in education.
The spending needed in 2030 to perform well in the health SDG are the level of expenditures Nigeria would incur by 2030 in light of projected demographics (the projected population share of infants and the elderly, who have greater medical needs) and if it matched, by 2030, today's levels of the health cost-drivers of the high performers among Nigeria's peers. These cost drivers include doctors' wages, the number of doctors relative to the population size, the number of other medical personnel relative to the population size, and health spending besides the health workers' wage bill. The approach of matching Nigeria's 2030 cost drivers to today's level of the high performers is seen in the corresponding columns of Table 2. Table AII.1 gives the data sources and computation of demographic factors and cost drivers for Nigeria in today (latest estimates available are from 2016-17).

Appendix III. Electric Power Generation, Transmission, and Distribution
We obtained power mix from the Nigeria's Federal Ministry of Power and the National Council on Power (NACOP). 51 The cost per kW of installed generation comes from international benchmarks. The average investment cost per kW of capacity is calculated as the weighted average of unit costs and share of installed capacity in the power mix.
The unit cost per kW is estimated at US$ 1,092.  Based on interviews with experts the costs in transmission and distribution costs are assumed to add 50 percent each to investment costs in capacity. We also assumed that investment costs in power storage will be offset by lower transmission and distribution costs. Therefore, the total costs of investment in electric power generation, transmission, and distribution were estimated at US$ 2,184 per kW.

Appendix IV. Roads Unit Cost per Kilometer of Road
We estimated the share of future highways-national and state-local (district, urban, and project), and rural roads from Nigeria's Infrastructure Concession Regulatory Commission. 52 The cost per type of road is taken from World Bank and African Development Bank projects as well as engineering estimates (Table AIV.1). We assumed that future roads are going to follow the same proportion. As a result, the average cost of road construction was estimated at US$550 thousand per kilometer.

Migration-Adjusted Rural Access Index
The Rural Access Index (RAI) is calculated based on a GIS model of the distribution of rural population, and a geospatial model of rural roads (including their location and type). Demographic dynamics affect the RAI even without additional roads. i.e., ceteris paribus, the migration from rural to urban areas increases mechanically the RAI. We account for demographic migration from rural to urban in 2030 areas to calculate the migration-adjusted RAI in 2030 keeping roads constant. The following equation presents the calculation:

Road Length Needed
Using a sample of low-income and emerging economies, we estimate the length of all-weather roads regressing road density on GDP per capita, population density, agriculture and manufacturing sector shares in the economy, urbanization rate, and migration-adjusted Rural Access Index-i.e., the share of the population that has access to road within two kilometers. This approach assumes away contemporaneous reverse causality: i.e., road density affects income per capita and population density with a substantial lag. 53 The regression specification is as follows: where lg_cia_density is natural logarithm of road density, lggdp_cap is the natural logarithm of GDP per capita, agg_gdp is the aggregated GDP, manu_gdp is the ratio of manufacturing to GDP, lgpop_density is the natural logarithm of population density, and urban is the share of urban population in total population. The regression is restricted to low-income and developing economies, and emerging market economies with medium-range road density (i.e., it does not incorporate advanced economies, or countries with too low or too high road density).
We then use the point estimates from the regression to calculate the additional kilometers of road needed given Nigeria's projected population and GDP per capita growth and the increase in the RAI from 31 (migration-adjusted) to at least 75 percent by 2030.
We estimate the total cost of the additional road network by multiplying the estimated additional kilometers by the unit cost of constructing one kilometer, which is set at US$ 550,308 per kilometer. 54 To account for depreciation, we increase the total cost of the additional kilometers by 5 percent. To avoid double counting and since the services are incremental (i.e., populations with safely managed sanitation have access to more basic services like water and latrines), we compute the total population unserved as the maximum of rural population unserved by type of service plus the maximum of urban population unserved by type of service. Following the WASH methodology developed by the World Bank, 55 the total cost was calculated as the full cost of providing safely managed water and sanitation services plus half of the cost of providing the basic water and sanitation.