placestats

Adult literacy vs. Median age

Fades after adjusting for income

Across 135 countries, Adult literacy and Median age rise and fall together at r = +0.68 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to +0.22, which could easily be chance (q = 0.20, allowing for the many pairs tested, and allowing for countries in the same region being alike). So the first figure mostly shows richer countries differing from poorer ones, not a link between these two things. Caution: direction is not consistent across regions.

Comparing countries across the middle half of median age, 20 to 33.8 years, adult literacy is better by 18.9% of adults at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 7.8% of adults.

Link before adjusting (r)+0.680p = 1.2e-19 · 135 countries
After adjusting for national income+0.224p = 0.009 · likely range [+0.06, +0.38]
p, allowing for regions0.002standard error 0.036 · 6 regions
Check for luck (q)0.197across 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
Median age · yearslink with income +0.86 · 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 →Median age · years →30.6%100%14.347.5Aruba: 96.8% of adults, 41 yearsAfghanistan: 37.3% of adults, 16.9 yearsAngola: 68.2% of adults, 16.5 yearsAlbania: 97.7% of adults, 36.3 yearsUnited Arab Emirates: 98.8% of adults, 31.2 yearsArgentina: 99.1% of adults, 32.1 yearsArmenia: 99.8% of adults, 35.8 yearsAzerbaijan: 99.8% of adults, 32.6 yearsBurundi: 71.3% of adults, 15.9 yearsBenin: 51.4% of adults, 17.8 yearsBurkina Faso: 41.6% of adults, 17.3 yearsBangladesh: 79% of adults, 25.3 yearsBulgaria: 98.3% of adults, 44.3 yearsBahrain: 97.8% of adults, 32.9 yearsBosnia and Herzegovina: 97% of adults, 44.9 yearsBelarus: 99.9% of adults, 40.5 yearsBelize: 87.9% of adults, 25.9 yearsBolivia: 96.7% of adults, 24.7 yearsBrazil: 94.7% of adults, 33.9 yearsBrunei Darussalam: 96.1% of adults, 31.8 yearsBhutan: 64.9% of adults, 29.4 yearsCentral African Republic: 42.4% of adults, 14.3 yearsChile: 96.4% of adults, 36 yearsChina: 96.7% of adults, 39.1 yearsCote d'Ivoire: 50% of adults, 18.1 yearsCameroon: 72.6% of adults, 17.8 yearsCongo, Dem. Rep.: 68.5% of adults, 15.8 yearsColombia: 95.3% of adults, 31.6 yearsComoros: 75.6% of adults, 20.3 yearsCabo Verde: 88.5% of adults, 27.9 yearsCosta Rica: 97.4% of adults, 34.1 yearsCayman Islands: 98.9% of adults, 37.9 yearsCyprus: 98.7% of adults, 37.8 yearsDominican Republic: 94% of adults, 27.7 yearsEcuador: 93.5% of adults, 28.4 yearsEgypt, Arab Rep.: 79.5% of adults, 24 yearsSpain: 99.7% of adults, 44.9 yearsEstonia: 99.9% of adults, 41.9 yearsEthiopia: 60.5% of adults, 18.7 yearsGabon: 88.9% of adults, 21.5 yearsGeorgia: 99.7% of adults, 36.8 yearsGhana: 76.5% of adults, 20.9 yearsGuinea: 39.6% of adults, 18 yearsGambia, The: 51.6% of adults, 18.2 yearsGuinea-Bissau: 63.9% of adults, 18.9 yearsGuatemala: 82.1% of adults, 22.6 yearsGuyana: 85.6% of adults, 25.6 yearsHonduras: 88.3% of adults, 23.5 yearsHaiti: 68% of adults, 23.5 yearsIndonesia: 96% of adults, 29.8 yearsIndia: 78.2% of adults, 28.1 yearsIran, Islamic Rep.: 88.9% of adults, 32.9 yearsIraq: 84.1% of adults, 20.3 yearsItaly: 99.3% of adults, 47.5 yearsJordan: 94.4% of adults, 24.3 yearsCambodia: 71.9% of adults, 25.8 yearsKiribati: 98.6% of adults, 22.7 yearsKuwait: 96.5% of adults, 34.5 yearsLao PDR: 75.6% of adults, 24.3 yearsLebanon: 92% of adults, 28.3 yearsLiberia: 59.4% of adults, 18.4 yearsSri Lanka: 92.7% of adults, 32.8 yearsLesotho: 90.4% of adults, 21.4 yearsLithuania: 99.8% of adults, 42.1 yearsLatvia: 99.9% of adults, 43.1 yearsMacao SAR, China: 96.5% of adults, 38.3 yearsMorocco: 64.3% of adults, 29.2 yearsMoldova: 99.4% of adults, 37.8 yearsMadagascar: 74.7% of adults, 18.9 yearsMaldives: 98.2% of adults, 31.1 yearsMexico: 95.6% of adults, 28.9 yearsMarshall Islands: 95.8% of adults, 20.7 yearsMali: 35.6% of adults, 15.5 yearsMalta: 93.3% of adults, 40.3 yearsMyanmar: 93.5% of adults, 29.5 yearsMontenegro: 98.5% of adults, 39.3 yearsMongolia: 98.6% of adults, 26.8 yearsMozambique: 61.7% of adults, 16.3 yearsMauritania: 59.5% of adults, 17.1 yearsMauritius: 94.3% of adults, 36.9 yearsMalawi: 70.2% of adults, 17.6 yearsMalaysia: 95.8% of adults, 30.1 yearsNamibia: 87.6% of adults, 21 yearsNiger: 35.6% of adults, 15.3 yearsNigeria: 70.4% of adults, 17.8 yearsNicaragua: 87.3% of adults, 25.3 yearsNepal: 68.7% of adults, 24.7 yearsNaoero: 96.6% of adults, 20.4 yearsOman: 97.3% of adults, 29.3 yearsPakistan: 58.9% of adults, 20.3 yearsPanama: 96.2% of adults, 29.6 yearsPeru: 93.7% of adults, 29.5 yearsPhilippines: 98.5% of adults, 25.3 yearsPalau: 99.8% of adults, 37.8 yearsPapua New Guinea: 87% of adults, 22.3 yearsPuerto Rico (US): 92.4% of adults, 45.3 yearsPortugal: 94.5% of adults, 46.2 yearsParaguay: 94.9% of adults, 26.3 yearsWest Bank and Gaza: 97.9% of adults, 19.8 yearsQatar: 97.8% of adults, 33.2 yearsRomania: 99.2% of adults, 42.6 yearsRussian Federation: 99.9% of adults, 39.5 yearsRwanda: 78.8% of adults, 19.4 yearsSaudi Arabia: 97.9% of adults, 29.2 yearsSenegal: 50.4% of adults, 19.1 yearsSingapore: 97.7% of adults, 35.1 yearsSierra Leone: 43.6% of adults, 19.3 yearsEl Salvador: 89.8% of adults, 27 yearsSan Marino: 99.9% of adults, 47.4 yearsSomalia, Fed. Rep.: 54.1% of adults, 15.4 yearsSerbia: 99.3% of adults, 43.9 yearsSao Tome and Principe: 87.4% of adults, 19.1 yearsSuriname: 92.9% of adults, 28.1 yearsEswatini: 90.8% of adults, 22 yearsSeychelles: 93.9% of adults, 33.7 yearsSyrian Arab Republic: 94.4% of adults, 22.2 yearsChad: 30.6% of adults, 15.4 yearsTogo: 72.6% of adults, 18.1 yearsThailand: 91.1% of adults, 39.7 yearsTurkmenistan: 99.9% of adults, 26.2 yearsTimor-Leste: 69.4% of adults, 21 yearsTonga: 99.5% of adults, 20.7 yearsTunisia: 86.3% of adults, 32.1 yearsTurkiye: 97.3% of adults, 32.5 yearsTuvalu: 100% of adults, 24.3 yearsTanzania: 78.2% of adults, 17.2 yearsUganda: 77% of adults, 16.5 yearsUruguay: 98.9% of adults, 35.8 yearsUzbekistan: 100% of adults, 26.9 yearsViet Nam: 96.1% of adults, 32.4 yearsVanuatu: 88% of adults, 20.1 yearsSamoa: 98% of adults, 19.9 yearsSouth Africa: 91.2% of adults, 28.2 yearsZambia: 71.8% of adults, 17.5 yearsZimbabwe: 93.2% of adults, 17.8 yearsESPITAMLINERPRIPRTPSESMRTCDTONWSM

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted+0.6801.2e-19135
By rank (Spearman), not adjusted+0.7545.2e-26135
Standard (Pearson), adjusted for national income+0.2240.009135
By rank (Spearman), adjusted for national income+0.3454.5e-5135

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 135 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: +0.456 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from +0.194 (without GUY) to +0.238 (without WSM). 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: GUY (-0.029).

Fragile: this link may not hold up.
  • direction is not consistent across regions

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 & Pacific23-0.00
Europe & Central Asia23-0.25
Latin America & Caribbean24+0.23
Middle East, North Africa, Afghanistan & Pakistan18+0.01
Sub-Saharan Africa41+0.34

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 third45+0.51
Middle third45+0.12
Richest third45+0.33

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
Christians72+0.15
Muslims42+0.40

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
France22+0.59
Never a European colony16+0.20
Spain18-0.18
United Kingdom42+0.22

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 = +0.223 after dropping 5 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 34years. 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 = -0.154, 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 median age move with it.

Across countries (adjusted)+0.224for comparison
Within countries+0.553each country vs itself
…and vs the same year elsewhere-0.154q = 0.247 · 78 countries
Year-on-year changes-0.040q = 0.585
The direction flips. Comparing each country only with itself gives +0.55. Also taking out what happened to the whole world each year gives -0.15. So the first figure was picking up a trend both measures share with worldwide progress, not a link between them.
Read with care.
  • Almost all of the second indicator's variation is between countries, 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.

772 country-years (one country in one year), 78 countries, 1990–2023, about 10 years each on average. Share of the variation that happens within countries over time: 11% for Adult literacy, 7% for Median age. 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

0.30−0.3-100+10years Median age trails Adult literacy →lag -10: r = -0.211 (n = 725)lag -9: r = -0.207 (n = 732)lag -8: r = -0.192 (n = 736)lag -7: r = -0.179 (n = 739)lag -6: r = -0.163 (n = 751)lag -5: r = -0.161 (n = 754)lag -4: r = -0.156 (n = 758)lag -3: r = -0.157 (n = 765)lag -2: r = -0.161 (n = 771)lag -1: r = -0.140 (n = 792)lag +0: r = -0.154 (n = 772)lag +1: r = -0.156 (n = 739)lag +2: r = -0.125 (n = 697)lag +3: r = -0.126 (n = 656)lag +4: r = -0.122 (n = 611)lag +5: r = -0.199 (n = 538)lag +6: r = -0.194 (n = 474)lag +7: r = -0.214 (n = 413)lag +8: r = -0.147 (n = 362)lag +9: r = -0.117 (n = 317)lag +10: r = -0.055 (n = 275)

Same year (lag 0): -0.154. 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 (-0.21 at lag +7) is higher than the same-year one by 0.06. That gap is not a finding. It is the largest of 21 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
years		Years
Uzbekistan UZB100%26.92022, 2023
Tuvalu TUV100%24.32022, 2023
Russian Federation RUS99.9%39.52021, 2023
San Marino SMR99.9%47.42022, 2023
Turkmenistan TKM99.9%26.22022, 2023
Latvia LVA99.9%43.12011, 2023
Estonia EST99.9%41.92011, 2023
Belarus BLR99.9%40.52019, 2023
Palau PLW99.8%37.82020, 2023
Armenia ARM99.8%35.82023
Lithuania LTU99.8%42.12011, 2023
Azerbaijan AZE99.8%32.62023
Spain ESP99.7%44.92021, 2023
Georgia GEO99.7%36.82024, 2023
Tonga TON99.5%20.72023

World Bank, World Development Indicators
United Nations, Department of Economic and Social Affairs, Population Division: World Population Prospects 2024 and Estimates and Projections of Women of Reproductive Age Who Are Married or in a Union

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.

Median age

Median age of the population

United Nations Department of Economic and Social Affairs, Population Division · via Our World in Data · CC BY 3.0 IGO · updated biennial

The age that splits a population in half: half are older and half are younger. The shares aged under 15 and over 65 are already on the site. All three are treated as measuring the same thing. They are readings of the same age pyramid, so they are bound to match, and their agreement is not a finding. No "better" direction is set.

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 Median age

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

More links with Adult literacy or Median age