Human Development Index (HDI)

This article was first published in 2014. The last revision was made in November 2019.

The Human Development Index (HDI) is an index that measures key dimensions of human development. The three key dimensions are:1

A long and healthy life – measured by life expectancy.

Access to education – measured by expected years of schooling of children at school-entry age and mean years of schooling of the adult population.

And a decent standard of living – measured by Gross National Income per capita adjusted for the price level of the country.

This entry provides a basic overview of the Human Development Index over the last decades using the standard HDI methodology of the UNDP.

In addition we are looking at long-term development by relying on the Historical Index of Human Development (HIHD), developed by historian Leandro Prados de la Escosura.

The metrics of the HDI and HIHD are similar, but differ slightly in how they are used to derive the development index – details on these measures can be found in the Data Quality & Definitions section below.


On all aspects Our World in Data offers research and data in dedicated entries:

Here is the Our World in Data entry on life expectancy.

Here are our entries on Literacy and the Global Rise of Education.

And GNI per capita we discuss in our entry on Economic Growth.

The Human Development Index around the world

The HDI data is regularly published by the United Nations Development Programme.

The differences across the world are very large, ranging from the highest values in North America, Europe, Japan, and Oceania to the lowest in central Africa.

To explore the change over time you can move the timeline slider below the map.

Human development over time

Long run perspective from the Historical Index of Human Development

The economic historian Leandro Prados de la Escosura calculated the HDI over the course of two centuries. He refers to it as the ‘Historical Index of Human Development’.

This data is shown here to give a long run perspective on human development. As always on Our World in Data, you can add any other country to the chart.

Country-by-country perspective over the last three decades

The HDI is published by the United Nations Development Programme and this data is shown in the time-series chart here.

Add other countries to see the change over time or compare development between countries.

The components of the HDI

Health

Life expectancy

The first component of the HDI – a long and healthy life – is measured by life expectancy.

Long-run estimates of life expectancy across the world are shown in the visualization. For countries where historical records are available, such as the UK, estimates can extend as far back as 1543 – click on the UK to see this long-run perspective. Global and regional estimates extend back to the year 1770.

This dataset is based on a combination of data from the Clio Infra project, the UN Population Division, and global and estimates for world regions from James Riley (2005).2

You find more research in our entry on Life Expectancy.

Education

Expected and average years of schooling

The second component – access to education – is measured by expected years of schooling of children at school-entry age and mean years of schooling of the adult population.

Education has been one of the most integral drivers and outcomes of global development.

The provision of education is now viewed in most parts of the world as a basic right – with pressure on governments to ensure high-quality education for all.

There are many metrics we can use to assess education access, quality, and attainment – we cover many of them throughout our work on education.

The visualizations present the two metrics that the HDI captures:

  • Mean years of schooling estimates the average number of years of total schooling adults aged 25 years and older have received. This data extends back to the year 1870 and is based on the combination of data from Lee and Lee (2016); Barro-Lee (2018); and the UN Development Programme.
  • Expected years of schooling measures the number of years of schooling that a child of school entrance age can expect to receive if the current age-specific enrollment rates persist throughout the child’s life by country.

Standard of living

GNI per capita

The architects of the HDI have decided to add a third dimension – a decent standard of living – and to measure it by Gross National Income per capita.

For most of human history, our ancestors were stuck in a world of poor health, hunger and little access to formal education. Economic growth – particularly over the past few centuries – has allowed some part of the world population to break out of these conditions.

This metric is adjusted for price changes over time, and price differences between countries – it is measured in international-$ in 2011 prices.

The map shows the Gross National Income per capita – this is the metric that the HDI relies on.

You find more research in our entry on Economic Growth.

Human Development and GDP

HIHD vs. GDP per capita

This chart shows the Historical Index of Human Development (HIHD) plotted relative to average income (GDP per capita).

There is a very strong correlation with richer countries having a higher HIHD. This is partly the case because average income is itself one of the three dimensions measured by the HDI and partly because the other two dimensions – good education and good health – are correlated with GDP per capita.

HIHD with and without GDP

Because average income is itself one of the three dimensions measured by the HDI it makes sense to study the correlation without income as part of the composite index.

The chart here shows the comparison of the HIHD with and without the inclusion of the GDP per capita metric.

Countries which lie below or closer to the grey line (which indicates equal parity between these measures), have achieved improvements in these measures of development (health and education) with lower levels of GDP per capita relative to countries further from the line.

Overall, there is a strong correlation between the HDI measured with and without GDP per capita as an additional metric.

HIHD (without GDP metric) vs. GDP per capita

The chart here shows the Historical Index of Human Development (HIHD), renormalised without the GDP metric, plotted relative to average income (GDP per capita).

Data Quality & Definition

How is the Human Development Index calculated?

The Human Development Index (HDI) provides a single index measure to capture three key dimensions of human development: a long and healthy life, access to knowledge and a decent standard of living.

The HDI utilizes four key metrics:3

  • life expectancy at birth – to assess a long and healthy life
  • expected years of schooling – to assess access to knowledge of the young generation
  • average years of schooling – to assess access to knowledge of the older generation
  • gross national income (GNI) per capita – to assess the standard of living

There are two steps to calculating the HDI:

1. Forming indices for each of the four metrics

Values of each of the four metrics are first normalized to an index value of 0 to 1. To do this, “goalposts” of the maximum and minimum limits on each metrics are set by the UNDP, as shown in the table.

With the actual value for a given country, and the global maximum and minimum, the dimension (indices) value for each metric is calculated as:

Dimension~index=\frac{actual~value-minimum~value}{maximum~value-minimum~value}

The dimension index is therefore 1 in a country that achieves the maximum value and it is 0 for a country that is at the minimum value.

2. Aggregating the four metrics to produce the HDI

Once each of the individual indices have been calculated, they are aggregated to calculate the HDI.

The HDI is calculated as the geometric mean (equally-weighted) of life expectancy, education, and GNI per capita, as follows:

HDI= (I_{Health}*I_{Education}*I_{Income})^{1/3}

The education dimension is the arithmetic mean of the two education indices (mean years of schooling and expected years of schooling).

Screen shot 2018 05 08 at 13.55.26

How is the HIHD measured?

The Historical Index of Human Development (HIHD) was created by Leandro Prados de la Escosura, and provides a measure of human development from 1870 onwards.

The HIHD is based on a very similar premise to that of the HDI. It provides an indexed measure across the same three dimensions: a long and healthy life, access to knowledge and a decent standard of living.

The four indices used in calculation of the HIHD differ slightly from that of the HDI. They are:

  • life expectancy at birth (to assess a long and healthy life);
  • adult literacy (percentage of the population aged over 15 years who can read and write);
  • educational enrolment rates (percentage of population in the relevant age cohort enrolled in primary, secondary, and tertiary education);
  • gross domestic product (GDP) per capita (to assess standard of living).

To convert these metrics into indices between 0 and 1, the HIHD uses a different methodology from that of the HDI. Whereas the HDI scales these linearly using the actual values, and maximum and minimum bounds, the HIHD scales these non-linearly. The authors note: “As social variables (longevity and education) have upper and lower bounds (unlike GDP per head that has not known upper bound), they are transformed nonlinearly in order to allow for two main facts: that increases of the same absolute size represent greater achievements the higher the level at which they take place; and that quality improvements are associated to increases in quantity.” These variables are therefore scaled logarithmically:

I=(log(M-Mo)-log(M-x))/log(M-Mo)

Where: I is the dimension index, x is an indicator of a country’s standard of living, M and Mo are the maximum and minimum values, respectively, or goalposts, that facilitate comparisons over time and log stands for the natural logarithm. The index for each dimension ranges between 0 and 1.

Notice that this is a very different transformation than the HDI (as measured by the UNDP) which uses, I = (x – Mo) / (M – Mo).

The four indices are then combined to form the HIHD value using the geometric average:

HIHD= (I_{Health}*I_{Education}*I_{Income})^{1/3}

Comparison of HDI and HIHD

In the chart shown we see a comparison of the Human Development Index (HDI) and Historical Index of Human Development (HIHD), as described in the explanations above. Since all countries lie above the grey (parity) line, we see that countries tend to score higher on the HDI than the HIHD. However, if we look at changes through time, we see that although HIHD values are typically lower, they can change much more quickly since indices are derived non-linearly (on a logarithmic scaling).4

Data Sources

United Nations Development Programme
    • Data: The United Nations Development Programme is the institution that publishes the Human Development Index.
    • Geographical coverage: Globally – by country, world region, and HDI level
    • Time span: From 1980 onwards
    • Available at: United Nations Development Programme data page

Historical Index of Human Development (HIHD) by Leandro Prados de la Escosura