placestats

Adult literacy vs. Inequality-adjusted HDI

Holds up after adjusting for income

Across 120 countries, Adult literacy and Inequality-adjusted HDI rise and fall together at r = +0.83 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to +0.63 (q = 0.017, allowing for the many pairs tested). Much of the first figure is that both measures rise with national income, but a strong positive link remains.

Comparing countries across the middle half of inequality-adjusted hdi, 0.378 to 0.684 points, adult literacy is better by 26.8% of adults at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 35.7% of adults.

Link before adjusting (r)+0.835p = 2.5e-32 · 120 countries
After adjusting for national income+0.628p = 2.0e-14 · likely range [+0.51, +0.73]
p, allowing for regions0.003standard error 0.120 · 6 regions
Check for luck (q)0.017across 12,497 pairs

How to read these.r runs from −1 (one goes up as the other goes down) to +1 (they rise together), and 0 means no link. Adjusting for national income means comparing countries with the same GDP per person, so differences in wealth can’t explain the link. Income is used in percentage terms, since an extra $1,000 means more to a poor country than to a rich one. p is how likely a link this strong would be if there were really none. Below 0.05 means it is unlikely to be chance. Very small values are written in short form: 1.1e-32 means a decimal point followed by 31 zeros and then 11, so very close to zero. The likely range is where the true figure probably lies, and a range that crosses zero means the link could easily be chance. Countries in the same region tend to resemble each other, so the third figure allows for that, which gives a fairer p. The standard error is the typical size of the error in r. Finally, testing this many pairs means some will look strong by luck alone. A q below 0.05 means this link is unlikely to be one of those.

Adult literacy · % of adultslink with income +0.73 · high
Inequality-adjusted HDI · index, 0 to 1link with income +0.94 · proxy

Both of these rise and fall closely with national income, so a strong link between them before adjusting was close to certain. Read the adjusted figure, not the first one.

“Link with income” is how closely each measure tracks GDP per person across countries, from −1 to +1.

Every country as a dot

Adult literacy · % of adults →Inequality-adjusted HDI · index, 0 to 1 →30.6%100%0.2290.866Afghanistan: 37.3% of adults, 0.321 index, 0 to 1Angola: 68.2% of adults, 0.36 index, 0 to 1Albania: 97.7% of adults, 0.705 index, 0 to 1United Arab Emirates: 98.8% of adults, 0.866 index, 0 to 1Argentina: 99.1% of adults, 0.761 index, 0 to 1Armenia: 99.8% of adults, 0.743 index, 0 to 1Azerbaijan: 99.8% of adults, 0.735 index, 0 to 1Burundi: 71.3% of adults, 0.286 index, 0 to 1Benin: 51.4% of adults, 0.316 index, 0 to 1Burkina Faso: 41.6% of adults, 0.273 index, 0 to 1Bangladesh: 79% of adults, 0.482 index, 0 to 1Bulgaria: 98.3% of adults, 0.748 index, 0 to 1Bosnia and Herzegovina: 97% of adults, 0.689 index, 0 to 1Belarus: 99.9% of adults, 0.771 index, 0 to 1Bolivia: 96.7% of adults, 0.578 index, 0 to 1Brazil: 94.7% of adults, 0.594 index, 0 to 1Brunei Darussalam: 96.1% of adults, 0.756 index, 0 to 1Bhutan: 64.9% of adults, 0.478 index, 0 to 1Central African Republic: 42.4% of adults, 0.253 index, 0 to 1Chile: 96.4% of adults, 0.723 index, 0 to 1China: 96.7% of adults, 0.67 index, 0 to 1Cote d'Ivoire: 50% of adults, 0.35 index, 0 to 1Cameroon: 72.6% of adults, 0.361 index, 0 to 1Congo, Dem. Rep.: 68.5% of adults, 0.341 index, 0 to 1Colombia: 95.3% of adults, 0.593 index, 0 to 1Comoros: 75.6% of adults, 0.356 index, 0 to 1Cabo Verde: 88.5% of adults, 0.478 index, 0 to 1Costa Rica: 97.4% of adults, 0.678 index, 0 to 1Cyprus: 98.7% of adults, 0.841 index, 0 to 1Dominican Republic: 94% of adults, 0.634 index, 0 to 1Ecuador: 93.5% of adults, 0.64 index, 0 to 1Egypt, Arab Rep.: 79.5% of adults, 0.582 index, 0 to 1Spain: 99.7% of adults, 0.819 index, 0 to 1Estonia: 99.9% of adults, 0.841 index, 0 to 1Ethiopia: 60.5% of adults, 0.326 index, 0 to 1Gabon: 88.9% of adults, 0.558 index, 0 to 1Georgia: 99.7% of adults, 0.754 index, 0 to 1Ghana: 76.5% of adults, 0.399 index, 0 to 1Guinea: 39.6% of adults, 0.302 index, 0 to 1Gambia, The: 51.6% of adults, 0.329 index, 0 to 1Guinea-Bissau: 63.9% of adults, 0.331 index, 0 to 1Guatemala: 82.1% of adults, 0.479 index, 0 to 1Honduras: 88.3% of adults, 0.496 index, 0 to 1Haiti: 68% of adults, 0.337 index, 0 to 1Indonesia: 96% of adults, 0.608 index, 0 to 1India: 78.2% of adults, 0.475 index, 0 to 1Iran, Islamic Rep.: 88.9% of adults, 0.643 index, 0 to 1Iraq: 84.1% of adults, 0.534 index, 0 to 1Italy: 99.3% of adults, 0.817 index, 0 to 1Jordan: 94.4% of adults, 0.637 index, 0 to 1Cambodia: 71.9% of adults, 0.444 index, 0 to 1Kiribati: 98.6% of adults, 0.535 index, 0 to 1Lao PDR: 75.6% of adults, 0.462 index, 0 to 1Liberia: 59.4% of adults, 0.326 index, 0 to 1Sri Lanka: 92.7% of adults, 0.63 index, 0 to 1Lesotho: 90.4% of adults, 0.357 index, 0 to 1Lithuania: 99.8% of adults, 0.812 index, 0 to 1Latvia: 99.9% of adults, 0.812 index, 0 to 1Morocco: 64.3% of adults, 0.517 index, 0 to 1Moldova: 99.4% of adults, 0.719 index, 0 to 1Madagascar: 74.7% of adults, 0.319 index, 0 to 1Maldives: 98.2% of adults, 0.602 index, 0 to 1Mexico: 95.6% of adults, 0.646 index, 0 to 1Marshall Islands: 95.8% of adults, 0.626 index, 0 to 1Mali: 35.6% of adults, 0.281 index, 0 to 1Malta: 93.3% of adults, 0.843 index, 0 to 1Myanmar: 93.5% of adults, 0.477 index, 0 to 1Montenegro: 98.5% of adults, 0.771 index, 0 to 1Mongolia: 98.6% of adults, 0.647 index, 0 to 1Mozambique: 61.7% of adults, 0.297 index, 0 to 1Mauritania: 59.5% of adults, 0.374 index, 0 to 1Mauritius: 94.3% of adults, 0.669 index, 0 to 1Malawi: 70.2% of adults, 0.365 index, 0 to 1Malaysia: 95.8% of adults, 0.707 index, 0 to 1Namibia: 87.6% of adults, 0.438 index, 0 to 1Niger: 35.6% of adults, 0.265 index, 0 to 1Nigeria: 70.4% of adults, 0.379 index, 0 to 1Nicaragua: 87.3% of adults, 0.535 index, 0 to 1Nepal: 68.7% of adults, 0.437 index, 0 to 1Naoero: 96.6% of adults, 0.599 index, 0 to 1Oman: 97.3% of adults, 0.75 index, 0 to 1Pakistan: 58.9% of adults, 0.364 index, 0 to 1Panama: 96.2% of adults, 0.664 index, 0 to 1Peru: 93.7% of adults, 0.633 index, 0 to 1Philippines: 98.5% of adults, 0.597 index, 0 to 1Palau: 99.8% of adults, 0.616 index, 0 to 1Papua New Guinea: 87% of adults, 0.423 index, 0 to 1Portugal: 94.5% of adults, 0.795 index, 0 to 1Paraguay: 94.9% of adults, 0.599 index, 0 to 1West Bank and Gaza: 97.9% of adults, 0.538 index, 0 to 1Romania: 99.2% of adults, 0.758 index, 0 to 1Russian Federation: 99.9% of adults, 0.758 index, 0 to 1Rwanda: 78.8% of adults, 0.399 index, 0 to 1Senegal: 50.4% of adults, 0.34 index, 0 to 1Singapore: 97.7% of adults, 0.823 index, 0 to 1Sierra Leone: 43.6% of adults, 0.281 index, 0 to 1El Salvador: 89.8% of adults, 0.555 index, 0 to 1Somalia, Fed. Rep.: 54.1% of adults, 0.229 index, 0 to 1Serbia: 99.3% of adults, 0.772 index, 0 to 1Sao Tome and Principe: 87.4% of adults, 0.478 index, 0 to 1Eswatini: 90.8% of adults, 0.431 index, 0 to 1Seychelles: 93.9% of adults, 0.755 index, 0 to 1Syrian Arab Republic: 94.4% of adults, 0.419 index, 0 to 1Chad: 30.6% of adults, 0.252 index, 0 to 1Togo: 72.6% of adults, 0.363 index, 0 to 1Thailand: 91.1% of adults, 0.677 index, 0 to 1Timor-Leste: 69.4% of adults, 0.451 index, 0 to 1Tonga: 99.5% of adults, 0.682 index, 0 to 1Tunisia: 86.3% of adults, 0.595 index, 0 to 1Turkiye: 97.3% of adults, 0.708 index, 0 to 1Tuvalu: 100% of adults, 0.578 index, 0 to 1Tanzania: 78.2% of adults, 0.391 index, 0 to 1Uganda: 77% of adults, 0.4 index, 0 to 1Uruguay: 98.9% of adults, 0.747 index, 0 to 1Viet Nam: 96.1% of adults, 0.641 index, 0 to 1Vanuatu: 88% of adults, 0.521 index, 0 to 1Samoa: 98% of adults, 0.609 index, 0 to 1South Africa: 91.2% of adults, 0.476 index, 0 to 1Zambia: 71.8% of adults, 0.361 index, 0 to 1Zimbabwe: 93.2% of adults, 0.406 index, 0 to 1AFGARECYPESTLSOMLIMLTNERSYRTCDZWE

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted+0.8352.5e-32120
By rank (Spearman), not adjusted+0.8822.0e-40120
Standard (Pearson), adjusted for national income+0.6282.0e-14120
By rank (Spearman), adjusted for national income+0.7313.7e-21120

The rank version uses only each country’s place in line, from lowest to highest, so a few extreme countries count for less. The adjusted and unadjusted versions use the same 120 countries: those that report both measures and GDP per person. So the gap between them comes from the adjustment, not from a change in which countries are counted. Drop in the size of r after adjusting: +0.206 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from +0.610 (without KIR) to +0.647 (without AFG). The bar above shows that range on a scale from −1 to +1, with the solid line at the full result. The single country that moves r most: AFG (+0.018).

Within each region

Countries are not separate, unrelated cases, and neighbors share a lot. A link that holds inside each region is far more believable than one that shows up only when comparing regions.

nr
East Asia & Pacific22+0.74
Europe & Central Asia20+0.43
Latin America & Caribbean18+0.60
Middle East, North Africa, Afghanistan & Pakistan13+0.56
Sub-Saharan Africa41+0.64

By income third

If the link shows up only in the richest third of countries, it is a feature of rich countries, not a general pattern.

nr
Poorest third40+0.80
Middle third40+0.77
Richest third40+0.53

By largest religious group

Countries grouped by a label they share, such as main religion, rather than by a number. Groups of fewer than twelve countries are not shown. These groups differ in income, region and history all at once. So a gap between them is a place to start asking questions, not an answer.

nr
Christians67+0.47
Muslims35+0.68

By last european coloniser

Countries grouped by a label they share, such as main religion, rather than by a number. Groups of fewer than twelve countries are not shown. These groups differ in income, region and history all at once. So a gap between them is a place to start asking questions, not an answer.

nr
France21+0.77
Never a European colony13+0.45
Spain18+0.47
United Kingdom37+0.66

Without outliers (countries far outside the middle half of countries on either measure, by more than one and a half times the width of that middle half): r = +0.625 after dropping 1 countries.

Two series, one country

Both measures over the years for one country you pick. The two charts are stacked so they share only the years along the bottom.

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Over time, within countries

Everything above compares countries with each other at one moment. This section compares each country only with itself over 14years. So a link here can’t come from anything about a country that stays the same, such as its history, geography, institutions or culture.

Within countries over time, there is no link that is clearly more than chance (r = +0.175, comparing each country only with itself over the years, and each year only with the same year elsewhere). Whatever the cross-country picture shows, countries whose adult literacy moved did not tend to see their inequality-adjusted hdi move with it.

Across countries (adjusted)+0.628for comparison
Within countries+0.501each country vs itself
…and vs the same year elsewhere+0.175q = 0.221 · 48 countries
Year-on-year changes+0.008q = 0.947
Read with care.
  • Almost all of this indicator's variation is between countries, not within them, so the within-country estimate rests on a small part of the data.
  • Much of the within-country association disappears once shared global year effects are removed, which points to a common worldwide trend rather than a country-level relationship.

391 country-years (one country in one year), 48 countries, 2010–2023, about 8 years each on average. Share of the variation that happens within countries over time: 2% for Adult literacy, 3% for Inequality-adjusted HDI. The margins of error allow for each country appearing many times, and for each year’s value being close to the year before.

Year-to-year changes are a cautious test, not a final answer. Looking only at changes from one year to the next removes each country’s own trends. But it also makes measurement mistakes louder, which pulls the results toward zero. A near-zero result here is weak evidence of no link, not proof.

With one measure years behind the other

0.30−0.3-40+10years Inequality-adjusted HDI trails Adult literacy →lag -4: r = 0.009 (n = 242)lag -3: r = 0.046 (n = 285)lag -2: r = 0.100 (n = 335)lag -1: r = 0.128 (n = 378)lag +0: r = 0.175 (n = 391)lag +1: r = 0.242 (n = 383)lag +2: r = 0.123 (n = 366)lag +3: r = 0.199 (n = 356)lag +4: r = 0.166 (n = 362)lag +5: r = 0.198 (n = 325)lag +6: r = 0.226 (n = 286)lag +7: r = 0.185 (n = 284)lag +8: r = 0.122 (n = 266)lag +9: r = 0.169 (n = 233)lag +10: r = 0.172 (n = 202)

Same year (lag 0): +0.175. A peak away from zero does not show which comes first. These series change slowly — this year’s value is close to last year’s. That makes the curve smooth and nearly symmetric, whatever produced the data. Even a sharp peak at one lag (a gap of some years) would not prove that one measure changes the other.

The largest value on this curve (+0.24 at lag +1) is higher than the same-year one by 0.07. That gap is not a finding. It is the largest of 15 closely related estimates, and picking the biggest of many tests always makes it look bigger. That is exactly why nothing on this site is ranked or chosen by lag.

The data


% of adults
index, 0 to 1		Years
Tuvalu TUV100%0.5782022, 2023
Russian Federation RUS99.9%0.7582021, 2023
Latvia LVA99.9%0.8122011, 2023
Estonia EST99.9%0.8412011, 2023
Belarus BLR99.9%0.7712019, 2023
Palau PLW99.8%0.6162020, 2023
Armenia ARM99.8%0.7432023
Lithuania LTU99.8%0.8122011, 2023
Azerbaijan AZE99.8%0.7352023
Spain ESP99.7%0.8192021, 2023
Georgia GEO99.7%0.7542024, 2023
Tonga TON99.5%0.6822023
Moldova MDA99.4%0.7192014, 2023
Italy ITA99.3%0.8172019, 2023
Serbia SRB99.3%0.7722022, 2023

World Bank, World Development Indicators
United Nations Development Programme, Human Development Report 2025

Sources

Adult literacy

Literacy rate, adult total (% of people ages 15 and above)

UNESCO Institute for Statistics · CC BY 4.0 · updated quarterly

Reported only in census or survey years for most countries, so the data are sparse and uneven rather than yearly.

Inequality-adjusted HDI

Inequality-adjusted Human Development Index

United Nations Development Programme, Human Development Report Office · via Our World in Data · CC BY 3.0 IGO · updated annual · comparable from 2010 only

The HDI marked down for how unequally each of its three parts is spread within the country. The gap between this and the HDI is what inequality costs, and that is the number worth reading. The level itself is the HDI again, with its parts flagged the same way.

How this was computed

Data used: most recent value in 2010-2025; values come from 2010–2024. To adjust for income, each measure is first predicted from GDP per person (in percentage terms, on a log scale) with a straight-line fit. Only what is left over is then compared. This is called a partial correlation. The line is drawn the standard way (ordinary least squares), which picks the line that comes closest to all the countries at once. The error margins allow for countries in the same region resembling each other, using 6 World Bank regions. The q-value corrects for testing all 12,497 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Adult literacy and Inequality-adjusted HDI

This page shows that two measures go together. It does not show that Adult literacy changes Inequality-adjusted HDI, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.

More links with Adult literacy or Inequality-adjusted HDI