placestats

Child stunting vs. PISA maths

Fades after adjusting for income

Across 64 countries, Child stunting and PISA maths rise and fall together at r = -0.53 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.29, which could easily be chance (q = 0.073, 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 pisa maths, 378 to 472 PISA points, child stunting is better by 6.67% of children under 5 at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 4.74% of children under 5.

Link before adjusting (r)-0.531p = 6.3e-6 · 64 countries
After adjusting for national income-0.290p = 0.021 · likely range [-0.50, -0.05]
p, allowing for regions0.100standard error 0.136 · 5 regions
Check for luck (q)0.073across 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.

Child stunting · % of children under 5link with income -0.80 · proxy
PISA maths · PISA pointslink with income +0.79 · high

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

Child stunting · % of children under 5 →PISA maths · PISA points →1%44.6%336575Albania: 7.4% of children under 5, 368 PISA pointsArgentina: 10.7% of children under 5, 378 PISA pointsAustralia: 3.1% of children under 5, 487 PISA pointsBelgium: 2.6% of children under 5, 489 PISA pointsBulgaria: 5.5% of children under 5, 417 PISA pointsBosnia and Herzegovina: 7.9% of children under 5, 406 PISA pointsBelarus: 1.1% of children under 5, 472 PISA pointsBrazil: 8.9% of children under 5, 379 PISA pointsBrunei Darussalam: 9.9% of children under 5, 442 PISA pointsChile: 1.7% of children under 5, 412 PISA pointsColombia: 11.6% of children under 5, 383 PISA pointsCosta Rica: 10.6% of children under 5, 385 PISA pointsCzechia: 2.4% of children under 5, 487 PISA pointsGermany: 2.2% of children under 5, 475 PISA pointsDominican Republic: 5.6% of children under 5, 339 PISA pointsAlgeria: 8.9% of children under 5, 360 PISA pointsEstonia: 1.3% of children under 5, 510 PISA pointsFinland: 1.7% of children under 5, 484 PISA pointsUnited Kingdom: 3.5% of children under 5, 489 PISA pointsGeorgia: 4.7% of children under 5, 390 PISA pointsGreece: 2% of children under 5, 430 PISA pointsGuatemala: 44.6% of children under 5, 344 PISA pointsIndonesia: 22.6% of children under 5, 366 PISA pointsIreland: 2.2% of children under 5, 492 PISA pointsJamaica: 6.9% of children under 5, 377 PISA pointsJordan: 7.7% of children under 5, 361 PISA pointsJapan: 5.2% of children under 5, 536 PISA pointsKazakhstan: 4.4% of children under 5, 425 PISA pointsCambodia: 22% of children under 5, 336 PISA pointsKorea, Rep.: 1.8% of children under 5, 527 PISA pointsLebanon: 10.1% of children under 5, 393 PISA pointsLithuania: 1.6% of children under 5, 475 PISA pointsLatvia: 1.7% of children under 5, 483 PISA pointsMorocco: 13.7% of children under 5, 365 PISA pointsMoldova: 4.2% of children under 5, 414 PISA pointsMexico: 13.1% of children under 5, 395 PISA pointsNorth Macedonia: 3.8% of children under 5, 389 PISA pointsMalta: 3.5% of children under 5, 466 PISA pointsMontenegro: 8% of children under 5, 406 PISA pointsMongolia: 7.1% of children under 5, 425 PISA pointsMalaysia: 24.3% of children under 5, 409 PISA pointsNetherlands: 1.6% of children under 5, 493 PISA pointsPanama: 14% of children under 5, 357 PISA pointsPeru: 10.6% of children under 5, 391 PISA pointsPhilippines: 27.7% of children under 5, 355 PISA pointsPoland: 1% of children under 5, 489 PISA pointsPortugal: 3.2% of children under 5, 472 PISA pointsParaguay: 3.2% of children under 5, 338 PISA pointsWest Bank and Gaza: 8% of children under 5, 366 PISA pointsQatar: 5.4% of children under 5, 414 PISA pointsRomania: 7% of children under 5, 428 PISA pointsSaudi Arabia: 11.1% of children under 5, 389 PISA pointsSingapore: 2.8% of children under 5, 575 PISA pointsEl Salvador: 9.4% of children under 5, 343 PISA pointsSerbia: 4.6% of children under 5, 440 PISA pointsThailand: 12.3% of children under 5, 394 PISA pointsTrinidad and Tobago: 7.8% of children under 5, 417 PISA pointsTunisia: 8.9% of children under 5, 367 PISA pointsTurkiye: 5.5% of children under 5, 453 PISA pointsUkraine: 11.7% of children under 5, 441 PISA pointsUruguay: 6.5% of children under 5, 409 PISA pointsUnited States: 4.2% of children under 5, 465 PISA pointsUzbekistan: 6.7% of children under 5, 364 PISA pointsViet Nam: 19.2% of children under 5, 469 PISA pointsDOMESTGTMKHMKORPHLPRYSGPSLVVNM

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted-0.5316.3e-664
By rank (Spearman), not adjusted-0.6912.6e-1064
Standard (Pearson), adjusted for national income-0.2900.02164
By rank (Spearman), adjusted for national income-0.4240.00164

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 64 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: +0.241 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.353 (without VNM) to -0.261 (without PSE). 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: VNM (-0.063).

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 & Pacific12-0.53
Europe & Central Asia27-0.36
Latin America & Caribbean15-0.20

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 third22-0.16
Middle third21-0.43
Richest third21-0.67

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
Christians38-0.27
Muslims16-0.18

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
Spain14-0.15

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 = -0.308 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 20years. 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 = -0.278, 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 child stunting moved did not tend to see their pisa maths move with it.

Across countries (adjusted)-0.290for comparison
Within countries-0.194each country vs itself
…and vs the same year elsewhere-0.278q = 0.053 · 36 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.

232 country-years (one country in one year), 36 countries, 2003–2022, about 6 years each on average. Share of the variation that happens within countries over time: 5% for Child stunting, 7% for PISA maths. 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

0.40−0.4-20+6years PISA maths trails Child stunting →lag -2: r = -0.254 (n = 232)lag -1: r = -0.265 (n = 232)lag +0: r = -0.278 (n = 232)lag +1: r = -0.295 (n = 232)lag +2: r = -0.305 (n = 232)lag +3: r = -0.320 (n = 232)lag +4: r = -0.278 (n = 206)lag +5: r = -0.281 (n = 206)lag +6: r = -0.279 (n = 206)

Same year (lag 0): -0.278. 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 children under 5
PISA points		Years
Guatemala GTM44.6%3442024, 2022
Philippines PHL27.7%3552024, 2022
Malaysia MYS24.3%4092024, 2022
Indonesia IDN22.6%3662024, 2022
Cambodia KHM22%3362024, 2022
Viet Nam VNM19.2%4692024, 2022
Panama PAN14%3572024, 2022
Morocco MAR13.7%3652024, 2022
Mexico MEX13.1%3952024, 2022
Thailand THA12.3%3942024, 2022
Ukraine UKR11.7%4412024, 2022
Colombia COL11.6%3832024, 2022
Saudi Arabia SAU11.1%3892024, 2022
Argentina ARG10.7%3782024, 2022
Peru PER10.6%3912024, 2022

World Bank, World Development Indicators
OECD databases as named on each indicator: PISA, Social Expenditure Database (SOCX), Income Distribution Database, Development Assistance Committee statistics, Family Database, Government at a Glance, Corporate Tax Statistics, employment and environment statistics

Sources

Child stunting

Prevalence of stunting, height for age, modelled estimate (% of children under 5)

UNICEF, WHO and World Bank Joint Child Malnutrition Estimates · CC BY 4.0 · updated quarterly

An estimate from a statistical model. The agencies fit a model to household surveys and predict every country and year. So this is smoother than the surveys behind it, and it has values for years nobody measured. The survey-only series never reaches sixty countries in any year.

PISA maths

PISA mean mathematics score

OECD · via Our World in Data · CC BY 4.0 (OECD terms and conditions) · updated annual, except the snapshots noted per indicator

The average score of 15-year-olds on the same test in every country taking part. It is scaled so the OECD average in the starting year was 500, with a standard deviation (a typical gap between students) of 100. Held every three years. The 2021 round was held in 2022, and the OECD says it can still be compared with earlier rounds despite the pandemic. The three subjects are treated as measuring the same thing. Their links with each other are above 0.95, and that close match is a fact about the test, not about schooling.

How this was computed

Data used: most recent value in 2010-2025; values come from 2015–2024. 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 5 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 Child stunting and PISA maths

This page shows that two measures go together. It does not show that Child stunting changes PISA maths, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.

More links with Child stunting or PISA maths