IB DP Economics: Measuring development

This guide follows the IB Diploma Programme Economics guide (first assessment 2022, published February 2020), the course examined from the 2022 session onwards. It covers sub-topic 4.8, measuring development, in Unit 4 The global economy. All of 4.8 is SL and HL; it has no HL-only content. Every country, currency and figure here is invented and illustrative.

See the IB DP Economics hub and printable checklist. Condensed recall is in the revision notes and exam-style work in the practice set. To find weak spots first, try the free diagnostics. For GDP and GNI themselves, see measuring and managing the economy.

What 4.8 asks you to do

Topic	Skill to show	Level
Multidimensional nature of development	Explain why development is more than higher income	SL and HL
Single indicators	Explain GDP/GNI per person at PPP, health, education, inequality, energy and environmental indicators	SL and HL
Composite indicators	Explain HDI, GII, IHDI and the Happy Planet Index	SL and HL
Strengths and limitations	Evaluate the approaches	SL and HL
Growth and development	Evaluate the possible relationship	SL and HL

The guide marks the indicators as AO2 content, and the strengths, limitations and growth-development relationship as AO3. It lists no diagram or calculation for 4.8. The numbers below show how the indices behave, so you can explain them with confidence. Paper 1 does not allow calculators, so expect to interpret figures rather than compute an index; Papers 2 and 3 allow a four-function calculator or a GDC.

Growth, development and why one number is not enough

Economic growth is a rise in real output, usually shown by real GDP or GNI. Economic development is a broader improvement in how people live: longer lives, better health, education, security, fairness, choice and a sustainable environment. The guide describes economic well-being as multidimensional, and that idea is the starting point here.

Development has several dimensions:

• Income and material living standards: the ability to buy food, housing and services.
• Health and education: whether people live long and can learn.
• Equity: how widely gains are shared, including between women and men.
• Environment and energy: whether progress is secure for later generations.

No single statistic captures all of these, so economists use two kinds of measure: single indicators, which measure one aspect, and composite indicators, which combine several into one index.

Single indicators

GDP or GNI per person at PPP

Per person figures divide total income by population. Converting at the market exchange rate can mislead, because prices of non-traded goods and services are often lower in poorer countries. Purchasing power parity (PPP) converts incomes using the exchange rate that would let a standard basket of goods cost the same in both places.

Worked example (invented). In Tarvia a basket costs 2,400 taran. The same basket costs 800 units in a reference economy.

• PPP rate = 2,400 / 800 = 3 taran per unit.
• The market rate is 6 taran per unit. A GNI per person of 36,000 taran is 36,000 / 6 = 6,000 units at the market rate.
• At PPP it is 36,000 / 3 = 12,000 units.

The PPP figure is double because prices in Tarvia are half the reference level once converted at the market rate. PPP is the better guide to what income buys, though it still says nothing about who receives it.

Health and education indicators

Type	Examples	What it shows	Limit
Health	Life expectancy at birth; infant or under-five mortality; maternal mortality; doctors per 1,000 people; access to clean water	Whether people survive and are looked after	Averages hide regional and group gaps; quality of care is not shown
Education	Adult literacy; mean and expected years of schooling; school enrolment; completion rates	Whether people gain skills	Years in school do not show how much is learned

Economic and social inequality indicators

Examples are the Gini coefficient, the share of income held by the richest 10% or the poorest 40%, and gaps between women and men in pay, schooling or jobs. A Gini coefficient close to 0 means more equal incomes, and close to 1 means highly unequal. These show distribution, which GDP per person ignores. They do not tell you the level of income.

Energy and environmental indicators

• Energy: energy use per person, the share of households with electricity, and the share of energy from renewable sources. Access to electricity matters for health, schooling and business.
• Environmental: carbon dioxide emitted per person, ecological footprint, forest area, and air or water quality.

Higher energy use often goes with higher income, but more is not simply better: the source and the emissions matter too.

Composite indicators

A composite indicator turns several measures into one number so countries can be ranked and compared over time. The cost is that the weighting and the method are choices.

Human Development Index (HDI)

The HDI is built from three dimensions:

• Health: how long people can expect to live at birth.
• Education: mean years of schooling (adults) and expected years of schooling (children entering school).
• Standard of living: GNI per person at PPP.

Each dimension is turned into an index between 0 and 1: (actual value minus minimum) / (maximum minus minimum). The income index uses logarithms, so extra income counts for less as income rises. The overall HDI is the geometric mean of those three indices. The real method sets fixed minimum and maximum values; the ones below are illustrative.

Worked example (invented). Sorenth has life expectancy 72, expected schooling 12 years, mean schooling 8 years and GNI per person of 12,000 units at PPP. Illustrative limits: income from 200 to 80,000, expected schooling from 0 to 20, mean schooling from 0 to 15, life expectancy from 25 to 85.

• Health index = (72 - 25) / (85 - 25) = 47 / 60 = 0.783.
• Schooling indices: 12 / 20 = 0.600 and 8 / 15 = 0.533. Education index = their average = 0.567.
• Income index = (ln 12,000 - ln 200) / (ln 80,000 - ln 200) = 4.094 / 5.991 = 0.683.
• HDI = (0.783 x 0.567 x 0.683)^(1/3) = (0.3033)^(1/3) = 0.672.

Why geometric? It stops a strong dimension fully covering a weak one. Country A has indices 0.9, 0.9 and 0.3. Country B has 0.7, 0.7 and 0.7. Both have an arithmetic mean of 0.700. The geometric mean is 0.624 for A and 0.700 for B, so A is penalised for its weak dimension.

Inequality adjusted HDI (IHDI)

The IHDI starts from the HDI and adjusts each dimension for how unequally it is spread across people. If there is no inequality, IHDI equals HDI. Otherwise IHDI is lower, and the gap is the loss due to inequality.

Simplified worked example (invented). Sorenth has losses of 10% in health, 20% in education and 30% in income.

• Adjusted indices: 0.783 x 0.90 = 0.705; 0.567 x 0.80 = 0.453; 0.683 x 0.70 = 0.478.
• IHDI = (0.705 x 0.453 x 0.478)^(1/3) = 0.535.
• Loss = (0.672 - 0.535) / 0.672 = 20.4%.

The published method uses a specific inequality formula for each dimension; the idea you need is that unequal distribution lowers the score.

Gender Inequality Index (GII)

The GII measures disadvantage for women across three dimensions:

• Reproductive health: maternal mortality and adolescent births.
• Empowerment: women’s share of parliamentary seats, and secondary education attainment by gender.
• Labour market: women’s participation in the labour force.

It runs from 0 to 1, and a higher value means more inequality between women and men. Unlike the HDI, higher is worse.

Happy Planet Index

The Happy Planet Index asks how efficiently a country turns environmental resources into good lives. It combines life expectancy, reported well-being and inequality of outcomes, and relates them to ecological footprint. A country can score well with a modest income if people live long, report satisfaction and use few resources. It is the only listed index with sustainability built in, but reported well-being is subjective, and a poor country with a small footprint may score well despite hardship.

Strengths and limitations

Evaluate means weighing both sides. Use this table to build paragraphs and always tie a point to a named indicator.

Approach	Strengths	Limitations
GNI per person at PPP	Easy to find; compares purchasing power; shows scale	Ignores distribution, health, education, environment; informal activity often missed
Single social indicators	Direct measures of outcomes; easy to understand	Show one side only; averages hide gaps
HDI	Combines income, health and education; ranks easily	Omits inequality, freedom, environment; fixed weights; geometric mean and limits are choices
IHDI	Brings distribution in	More data needed; harder to explain
GII	Focuses on gender gaps	Leaves out many other gender gaps; limited to three dimensions
Happy Planet Index	Includes sustainability and well-being	Subjective data; can rank poor countries highly

Other limits apply to all indices: data quality varies, countries differ in what they value, and a ranking can hide that scores are close.

Growth and development: the possible relationship

Growth often helps development. Higher incomes raise tax revenue and household spending on health and schooling, and better-educated, healthier workers raise productivity, so development can also drive growth. The link is not automatic.

Worked comparison (invented). Tarvia and Quelland both have GNI per person of 22,000 units at PPP, so the income index is 0.785 in both.

Country	Life expectancy	Expected schooling	Mean schooling	HDI (illustrative limits)
Tarvia	70	13	9	0.716
Quelland	76	15	11	0.791

Same income, different outcomes. One possible reason (not shown by the data) is that Quelland spends more of its income on health and schools. Growth does not raise development where gains go to a few households, where governments spend little on public services, where growth causes pollution that harms health, or where weak institutions waste revenue. Development without growth is also hard to sustain, because spending needs funding.

A fair conclusion is that the relationship is positive but conditional. It depends on the sources of growth, how its gains are shared and how revenue is used, so check these in any case study you use.

Common errors

• Describing the HDI as an income measure. It combines health, education and income.
• Saying a higher GII is good. A higher GII means greater gender inequality.
• Treating PPP income as a measure of distribution. It is still an average.
• Listing strengths and limitations without applying them to a named indicator or country.
• Claiming growth always brings development, or never does.

Official syllabus

IB Diploma Programme Economics guide, first assessment 2022, published by the International Baccalaureate Organization (February 2020). This page covers sub-topic 4.8.