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Adult literacy vs. Pupil-teacher ratio

Fades after adjusting for income

Across 126 countries, Adult literacy and Pupil-teacher ratio rise and fall together at r = -0.73 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.41, which could easily be chance (q = 0.069, 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.

Comparing countries across the middle half of adult literacy, 74.9% to 97.7% of adults, pupil-teacher ratio is better by 12.6 pupils per teacher at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 6.32 pupils per teacher.

Link before adjusting (r)-0.735p = 1.2e-22 · 126 countries
After adjusting for national income-0.411p = 1.9e-6 · likely range [-0.55, -0.25]
p, allowing for regions0.009standard error 0.100 · 6 regions
Check for luck (q)0.069across 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
Pupil-teacher ratio · pupils per teacherlink with income -0.83 · 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 →Pupil-teacher ratio · pupils per teacher →30.6%100%6.9383.4Aruba: 96.8% of adults, 14.8 pupils per teacherAfghanistan: 37.3% of adults, 48.8 pupils per teacherAngola: 68.2% of adults, 50 pupils per teacherAlbania: 97.7% of adults, 17.6 pupils per teacherUnited Arab Emirates: 98.8% of adults, 24.5 pupils per teacherArmenia: 99.8% of adults, 15.4 pupils per teacherAzerbaijan: 99.8% of adults, 15.4 pupils per teacherBurundi: 71.3% of adults, 42.5 pupils per teacherBenin: 51.4% of adults, 39.2 pupils per teacherBurkina Faso: 41.6% of adults, 39.7 pupils per teacherBangladesh: 79% of adults, 30.1 pupils per teacherBulgaria: 98.3% of adults, 15.2 pupils per teacherBahrain: 97.8% of adults, 11.9 pupils per teacherBosnia and Herzegovina: 97% of adults, 16.9 pupils per teacherBelarus: 99.9% of adults, 19.2 pupils per teacherBelize: 87.9% of adults, 19.8 pupils per teacherBolivia: 96.7% of adults, 17.8 pupils per teacherBrazil: 94.7% of adults, 20.2 pupils per teacherBrunei Darussalam: 96.1% of adults, 9.9 pupils per teacherBhutan: 64.9% of adults, 34.7 pupils per teacherCentral African Republic: 42.4% of adults, 83.4 pupils per teacherChile: 96.4% of adults, 17.8 pupils per teacherChina: 96.7% of adults, 16.4 pupils per teacherCote d'Ivoire: 50% of adults, 41.8 pupils per teacherCameroon: 72.6% of adults, 44.8 pupils per teacherCongo, Dem. Rep.: 68.5% of adults, 33.2 pupils per teacherColombia: 95.3% of adults, 23.3 pupils per teacherComoros: 75.6% of adults, 28.1 pupils per teacherCabo Verde: 88.5% of adults, 21.1 pupils per teacherCosta Rica: 97.4% of adults, 12.2 pupils per teacherCayman Islands: 98.9% of adults, 15.7 pupils per teacherCyprus: 98.7% of adults, 12 pupils per teacherDominican Republic: 94% of adults, 18.9 pupils per teacherEcuador: 93.5% of adults, 24.3 pupils per teacherEgypt, Arab Rep.: 79.5% of adults, 23.7 pupils per teacherSpain: 99.7% of adults, 13.1 pupils per teacherEstonia: 99.9% of adults, 11.3 pupils per teacherEthiopia: 60.5% of adults, 55.1 pupils per teacherGabon: 88.9% of adults, 24.5 pupils per teacherGeorgia: 99.7% of adults, 8.98 pupils per teacherGhana: 76.5% of adults, 27 pupils per teacherGuinea: 39.6% of adults, 47.1 pupils per teacherGambia, The: 51.6% of adults, 36.1 pupils per teacherGuinea-Bissau: 63.9% of adults, 51.9 pupils per teacherGuatemala: 82.1% of adults, 20.3 pupils per teacherGuyana: 85.6% of adults, 23.2 pupils per teacherHonduras: 88.3% of adults, 25.6 pupils per teacherIndonesia: 96% of adults, 17 pupils per teacherIndia: 78.2% of adults, 32.7 pupils per teacherIran, Islamic Rep.: 88.9% of adults, 28.5 pupils per teacherItaly: 99.3% of adults, 11.5 pupils per teacherJordan: 94.4% of adults, 18.5 pupils per teacherCambodia: 71.9% of adults, 41.7 pupils per teacherKiribati: 98.6% of adults, 25.5 pupils per teacherKuwait: 96.5% of adults, 8.88 pupils per teacherLao PDR: 75.6% of adults, 22.3 pupils per teacherLebanon: 92% of adults, 12.5 pupils per teacherLiberia: 59.4% of adults, 22.3 pupils per teacherSri Lanka: 92.7% of adults, 21.7 pupils per teacherLesotho: 90.4% of adults, 32.9 pupils per teacherLithuania: 99.8% of adults, 13.5 pupils per teacherLatvia: 99.9% of adults, 11.5 pupils per teacherMacao SAR, China: 96.5% of adults, 13.5 pupils per teacherMorocco: 64.3% of adults, 26.8 pupils per teacherMoldova: 99.4% of adults, 17.9 pupils per teacherMadagascar: 74.7% of adults, 39.8 pupils per teacherMaldives: 98.2% of adults, 10.2 pupils per teacherMexico: 95.6% of adults, 26.6 pupils per teacherMali: 35.6% of adults, 37.8 pupils per teacherMalta: 93.3% of adults, 12.9 pupils per teacherMyanmar: 93.5% of adults, 24.4 pupils per teacherMongolia: 98.6% of adults, 30.4 pupils per teacherMozambique: 61.7% of adults, 55.3 pupils per teacherMauritania: 59.5% of adults, 34.3 pupils per teacherMauritius: 94.3% of adults, 16.2 pupils per teacherMalawi: 70.2% of adults, 58.7 pupils per teacherMalaysia: 95.8% of adults, 11.7 pupils per teacherNamibia: 87.6% of adults, 25.1 pupils per teacherNiger: 35.6% of adults, 36.3 pupils per teacherNigeria: 70.4% of adults, 37.6 pupils per teacherNicaragua: 87.3% of adults, 30.2 pupils per teacherNepal: 68.7% of adults, 19.7 pupils per teacherNaoero: 96.6% of adults, 40.2 pupils per teacherOman: 97.3% of adults, 9.67 pupils per teacherPakistan: 58.9% of adults, 44.1 pupils per teacherPanama: 96.2% of adults, 22 pupils per teacherPeru: 93.7% of adults, 17.4 pupils per teacherPhilippines: 98.5% of adults, 29.1 pupils per teacherPapua New Guinea: 87% of adults, 35.5 pupils per teacherPuerto Rico (US): 92.4% of adults, 13.5 pupils per teacherPortugal: 94.5% of adults, 12.4 pupils per teacherParaguay: 94.9% of adults, 24.2 pupils per teacherWest Bank and Gaza: 97.9% of adults, 24.5 pupils per teacherQatar: 97.8% of adults, 12.2 pupils per teacherRomania: 99.2% of adults, 19.3 pupils per teacherRussian Federation: 99.9% of adults, 21.3 pupils per teacherRwanda: 78.8% of adults, 59.5 pupils per teacherSaudi Arabia: 97.9% of adults, 13.8 pupils per teacherSenegal: 50.4% of adults, 36.3 pupils per teacherSingapore: 97.7% of adults, 14.7 pupils per teacherSierra Leone: 43.6% of adults, 27.5 pupils per teacherEl Salvador: 89.8% of adults, 26.9 pupils per teacherSan Marino: 99.9% of adults, 6.93 pupils per teacherSerbia: 99.3% of adults, 14.3 pupils per teacherSao Tome and Principe: 87.4% of adults, 31.2 pupils per teacherSuriname: 92.9% of adults, 13.4 pupils per teacherEswatini: 90.8% of adults, 26.6 pupils per teacherSeychelles: 93.9% of adults, 14.5 pupils per teacherChad: 30.6% of adults, 56.9 pupils per teacherTogo: 72.6% of adults, 40.1 pupils per teacherThailand: 91.1% of adults, 16.6 pupils per teacherTimor-Leste: 69.4% of adults, 26.9 pupils per teacherTonga: 99.5% of adults, 21.6 pupils per teacherTunisia: 86.3% of adults, 16.9 pupils per teacherTurkiye: 97.3% of adults, 17 pupils per teacherTuvalu: 100% of adults, 15.6 pupils per teacherTanzania: 78.2% of adults, 50.6 pupils per teacherUganda: 77% of adults, 42.7 pupils per teacherUruguay: 98.9% of adults, 11 pupils per teacherUzbekistan: 100% of adults, 21.5 pupils per teacherViet Nam: 96.1% of adults, 20.3 pupils per teacherVanuatu: 88% of adults, 26.6 pupils per teacherSamoa: 98% of adults, 30.2 pupils per teacherSouth Africa: 91.2% of adults, 30.3 pupils per teacherZambia: 71.8% of adults, 42.1 pupils per teacherZimbabwe: 93.2% of adults, 36.4 pupils per teacherAFGCAFESTGEOMLINERNRURWASLESMRTCD

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted-0.7351.2e-22126
By rank (Spearman), not adjusted-0.7451.6e-23126
Standard (Pearson), adjusted for national income-0.4111.9e-6126
By rank (Spearman), adjusted for national income-0.3662.7e-5126

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 126 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: +0.323 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.444 (without SLE) to -0.386 (without TCD). 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: SLE (-0.032).

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 & Pacific21-0.23
Europe & Central Asia21-0.04
Latin America & Caribbean22-0.36
Middle East, North Africa, Afghanistan & Pakistan16-0.70
Sub-Saharan Africa40-0.18

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 third42-0.35
Middle third42-0.41
Richest third42-0.28

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
Christians69-0.49
Muslims38-0.58

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
France20-0.31
Never a European colony15-0.34
Spain17-0.06
United Kingdom40-0.38

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 = -0.379 after dropping 6 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 30years. 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 = -0.165, 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 pupil-teacher ratio move with it.

Across countries (adjusted)-0.411for comparison
Within countries-0.489each country vs itself
…and vs the same year elsewhere-0.165q = 0.188 · 42 countries
Year-on-year changes—q = —
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.

356 country-years (one country in one year), 42 countries, 1990–2019, about 9 years each on average. Share of the variation that happens within countries over time: 5% for Adult literacy, 10% for Pupil-teacher ratio. 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+4years Pupil-teacher ratio trails Adult literacy →lag -10: r = 0.022 (n = 477)lag -9: r = 0.011 (n = 493)lag -8: r = -0.029 (n = 510)lag -7: r = -0.053 (n = 499)lag -6: r = -0.116 (n = 507)lag -5: r = -0.096 (n = 501)lag -4: r = -0.123 (n = 496)lag -3: r = -0.129 (n = 457)lag -2: r = -0.177 (n = 416)lag -1: r = -0.093 (n = 373)lag +0: r = -0.165 (n = 356)lag +1: r = -0.213 (n = 308)lag +2: r = -0.153 (n = 285)lag +3: r = -0.107 (n = 256)lag +4: r = -0.017 (n = 223)

Same year (lag 0): -0.165. 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 data


% of adults
pupils per teacher		Years
Uzbekistan UZB100%21.52022, 2018
Tuvalu TUV100%15.62022, 2018
Russian Federation RUS99.9%21.32021, 2017
San Marino SMR99.9%6.932022, 2018
Latvia LVA99.9%11.52011, 2017
Estonia EST99.9%11.32011, 2017
Belarus BLR99.9%19.22019, 2018
Armenia ARM99.8%15.42023, 2018
Lithuania LTU99.8%13.52011, 2017
Azerbaijan AZE99.8%15.42023, 2018
Spain ESP99.7%13.12021, 2017
Georgia GEO99.7%8.982024, 2018
Tonga TON99.5%21.62023, 2015
Moldova MDA99.4%17.92014, 2018
Italy ITA99.3%11.52019, 2017

World Bank, World Development Indicators
World Bank, World Development Indicators

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.

Pupil-teacher ratio

Pupil-teacher ratio, primary

UNESCO Institute for Statistics · CC BY 4.0 · updated quarterly

The World Bank's copy stops at 2019.

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 Pupil-teacher ratio

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

More links with Adult literacy or Pupil-teacher ratio