Two countries have nearly identical GNI per capita. Country A has high life expectancy and high educational attainment. Country B has low life expectancy and low educational attainment. What does HDI analysis predict?
ATheir HDI scores will be similar, since GNI per capita is the dominant HDI component
BCountry A will score significantly higher, demonstrating that policy choices in health and education determine human outcomes independently of income
CCountry B will score higher because lower baseline human development means it has more potential for measured improvement
DNeither country's HDI can be predicted without knowing the exact income figures to three decimal places
This scenario describes exactly what the HDI was designed to reveal: the divergence between income and human outcomes. Sri Lanka and Equatorial Guinea are the canonical real-world version of this comparison. The HDI uses a geometric mean of all three dimensions, so strong health and education performance gives Country A a much higher score even at the same income. This is the HDI's central insight — income alone does not determine human welfare; it depends critically on how income is invested in public health and education.
Question 2 Multiple Choice
Why does the HDI use a geometric mean of its three dimension indices rather than a simple arithmetic average?
AThe geometric mean is computationally simpler when combining indices expressed in different units
BA geometric mean ensures that very low performance on any single dimension substantially pulls down the overall score, preventing high income from fully compensating for poor health or education
CThe geometric mean gives extra weight to the income dimension, which the UNDP considers most important for development
DThe geometric mean eliminates the need to normalize each dimension to a 0–1 scale before combining
The switch from arithmetic to geometric mean (made in 2010) was deliberate. With an arithmetic mean, a very low score in one dimension (say, health = 0.1) can be offset by high scores in others. With a geometric mean, a near-zero score drags the overall product toward zero regardless of the other dimensions. This reflects a normative choice: a long life, knowledge, and a decent standard of living are not perfect substitutes — extreme deprivation in any one cannot be 'averaged away' by abundance in another.
Question 3 True / False
A country with very high oil revenues and GNI per capita will necessarily have a high HDI score.
TTrue
FFalse
Answer: False
Equatorial Guinea is the textbook counterexample. It has some of the highest per capita GNI in sub-Saharan Africa from oil revenues, yet scores poorly on the HDI because that income is concentrated among elites while most citizens lack access to basic healthcare and education. The geometric mean means that low scores on the health and education dimensions substantially depress the overall HDI even when income is high. High income is neither sufficient nor necessary for high human development — policy choices about distribution and investment in public goods are equally decisive.
Question 4 True / False
The HDI's education dimension combines two indicators: mean years of schooling for current adults and expected years of schooling for children entering school today.
TTrue
FFalse
Answer: True
The two-indicator approach is intentional. Mean years of schooling for adults captures the *existing stock* of human capital in the current workforce — what has already been achieved. Expected years of schooling for children captures the system's current *trajectory* — what it is promising the next generation. Using both gives a richer picture than a single indicator: a country might have a highly educated adult population from past investment but a collapsing school system, or vice versa. Earlier HDI versions used adult literacy rate, which was replaced to better capture both quantity and quality of education.
Question 5 Short Answer
Explain what the comparison between Sri Lanka and Equatorial Guinea reveals about the relationship between income and human development, and why this is the HDI's core insight.
Think about your answer, then reveal below.
Model answer: Sri Lanka has modest per capita income but achieves high HDI scores through strong public investment in free healthcare and universal education, translating limited resources into long lives and an educated population. Equatorial Guinea has much higher per capita income from oil but scores poorly because that wealth is concentrated among elites while most citizens lack basic health and education services. This comparison demonstrates the HDI's central insight: income is not destiny — the same level of national income can produce dramatically different human outcomes depending on whether it is distributed equitably and invested in public goods. This finding challenges income-centric development frameworks and supports the capabilities approach: what matters is not just what a country earns, but whether that translates into people living long, healthy, and educated lives. The HDI makes this gap visible and politically consequential.