placestats

Adult obesity vs. PISA maths

Holds up after adjusting for income

Across 84 countries, Adult obesity and PISA maths rise and fall together at r = -0.39 (on a scale from −1 to +1, where 0 means no link). It holds up almost unchanged when only countries with similar income (GDP per person) are compared (r = -0.51, q = 0.050, allowing for the many pairs tested).

Comparing countries across the middle half of PISA maths, 389 to 480 PISA points, adult obesity is better by 5.76% of adults at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 11.7% of adults.

Link before adjusting (r)-0.390p = 0.000 · 84 countries
After adjusting for national income-0.511p = 7.8e-7 · likely range [-0.65, -0.33]
p, allowing for regions0.005standard error 0.090 · 5 regions
Check for luck (q)0.050across 17,292 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 obesity · % of adultslink with income +0.34 · moderate
PISA maths · PISA pointslink with income +0.79 · high

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

Every country as a dot

Adult obesity · % of adults →PISA maths · PISA points →2.4%42%336575Albania: 24.1% of adults, 368 PISA pointsUnited Arab Emirates: 31.6% of adults, 431 PISA pointsArgentina: 37.2% of adults, 378 PISA pointsAustralia: 30.6% of adults, 487 PISA pointsAustria: 16.5% of adults, 487 PISA pointsBelgium: 20.8% of adults, 489 PISA pointsBulgaria: 20.3% of adults, 417 PISA pointsBosnia and Herzegovina: 21% of adults, 406 PISA pointsBelarus: 20.6% of adults, 472 PISA pointsBrazil: 30.1% of adults, 379 PISA pointsBrunei Darussalam: 37.1% of adults, 442 PISA pointsCanada: 26% of adults, 497 PISA pointsSwitzerland: 11.3% of adults, 508 PISA pointsChile: 40.5% of adults, 412 PISA pointsColombia: 24.9% of adults, 383 PISA pointsCosta Rica: 32.7% of adults, 385 PISA pointsCyprus: 21.6% of adults, 418 PISA pointsCzechia: 26.3% of adults, 487 PISA pointsGermany: 20.6% of adults, 475 PISA pointsDenmark: 14.3% of adults, 489 PISA pointsDominican Republic: 30.8% of adults, 339 PISA pointsAlgeria: 23.6% of adults, 360 PISA pointsSpain: 15.3% of adults, 473 PISA pointsEstonia: 20.3% of adults, 510 PISA pointsFinland: 24.2% of adults, 484 PISA pointsFrance: 11.2% of adults, 474 PISA pointsUnited Kingdom: 27.4% of adults, 489 PISA pointsGeorgia: 35.7% of adults, 390 PISA pointsGreece: 27.4% of adults, 430 PISA pointsGuatemala: 28% of adults, 344 PISA pointsCroatia: 30.8% of adults, 463 PISA pointsHungary: 31.4% of adults, 473 PISA pointsIndonesia: 11.8% of adults, 366 PISA pointsIreland: 27.9% of adults, 492 PISA pointsIceland: 22.2% of adults, 459 PISA pointsIsrael: 22.2% of adults, 458 PISA pointsItaly: 14% of adults, 471 PISA pointsJamaica: 35.2% of adults, 377 PISA pointsJordan: 35.4% of adults, 361 PISA pointsJapan: 5.9% of adults, 536 PISA pointsKazakhstan: 21.1% of adults, 425 PISA pointsCambodia: 4.92% of adults, 336 PISA pointsKorea, Rep.: 8.37% of adults, 527 PISA pointsLebanon: 30.7% of adults, 393 PISA pointsLithuania: 21.3% of adults, 475 PISA pointsLuxembourg: 19% of adults, 483 PISA pointsLatvia: 22.3% of adults, 483 PISA pointsMorocco: 21.6% of adults, 365 PISA pointsMoldova: 22.3% of adults, 414 PISA pointsMexico: 37.4% of adults, 395 PISA pointsNorth Macedonia: 26.8% of adults, 389 PISA pointsMalta: 30.6% of adults, 466 PISA pointsMontenegro: 17.1% of adults, 406 PISA pointsMongolia: 25.1% of adults, 425 PISA pointsMalaysia: 23.3% of adults, 409 PISA pointsNetherlands: 14.7% of adults, 493 PISA pointsNorway: 20.2% of adults, 468 PISA pointsNew Zealand: 34% of adults, 479 PISA pointsPanama: 37.7% of adults, 357 PISA pointsPeru: 29.2% of adults, 391 PISA pointsPhilippines: 9.62% of adults, 355 PISA pointsPoland: 21.8% of adults, 489 PISA pointsPortugal: 18.1% of adults, 472 PISA pointsParaguay: 34.7% of adults, 338 PISA pointsWest Bank and Gaza: 37.4% of adults, 366 PISA pointsQatar: 42% of adults, 414 PISA pointsRomania: 32.4% of adults, 428 PISA pointsRussian Federation: 17.6% of adults, 488 PISA pointsSaudi Arabia: 40.1% of adults, 389 PISA pointsSingapore: 17% of adults, 575 PISA pointsEl Salvador: 32.2% of adults, 343 PISA pointsSerbia: 21.8% of adults, 440 PISA pointsSlovak Republic: 26.1% of adults, 464 PISA pointsSlovenia: 19.8% of adults, 485 PISA pointsSweden: 17.5% of adults, 482 PISA pointsThailand: 16.4% of adults, 394 PISA pointsTrinidad and Tobago: 30.9% of adults, 417 PISA pointsTunisia: 26.1% of adults, 367 PISA pointsTurkiye: 28.8% of adults, 453 PISA pointsUkraine: 22.8% of adults, 441 PISA pointsUruguay: 34.9% of adults, 409 PISA pointsUnited States: 41% of adults, 465 PISA pointsUzbekistan: 31.2% of adults, 364 PISA pointsViet Nam: 2.4% of adults, 469 PISA pointsIDNJPNKHMKORNZLPANPHLPRYPSESGPUSA

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted-0.3900.00084
By rank (Spearman), not adjusted-0.4343.6e-584
Standard (Pearson), adjusted for national income-0.5117.8e-784
By rank (Spearman), adjusted for national income-0.4833.7e-684

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 84 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: -0.122 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.551 (without PSE) to -0.472 (without VNM). 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 (+0.040).

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 & Pacific13-0.67
Europe & Central Asia43-0.25
Latin America & Caribbean15+0.01

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 third28-0.28
Middle third28-0.59
Richest third28-0.65

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
Christians55-0.44
Muslims17-0.03

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
Spain14-0.04
United Kingdom14-0.50

By official ideology

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
No strong official ideology64-0.36

By party system

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
No parties banned70-0.40

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 = -0.472 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 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 = +0.140, 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 obesity moved did not tend to see their PISA maths move with it.

Across countries (adjusted)-0.511for comparison
Within countries-0.093each country vs itself
…and vs the same year elsewhere+0.140q = 0.274 · 54 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.

353 country-years (one country in one year), 54 countries, 2003–2022, about 7 years each on average. Share of the variation that happens within countries over time: 5% for Adult obesity, 10% 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

0.20−0.2-60+10years PISA maths trails Adult obesity →lag -6: r = -0.011 (n = 286)lag -5: r = 0.005 (n = 286)lag -4: r = 0.022 (n = 286)lag -3: r = 0.040 (n = 286)lag -2: r = 0.115 (n = 353)lag -1: r = 0.128 (n = 353)lag +0: r = 0.140 (n = 353)lag +1: r = 0.150 (n = 353)lag +2: r = 0.157 (n = 353)lag +3: r = 0.162 (n = 353)lag +4: r = 0.164 (n = 353)lag +5: r = 0.163 (n = 353)lag +6: r = 0.157 (n = 353)lag +7: r = 0.148 (n = 353)lag +8: r = 0.138 (n = 353)lag +9: r = 0.125 (n = 353)lag +10: r = 0.110 (n = 353)

Same year (lag 0): +0.140. 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
PISA points		Years
Qatar QAT42%4142024, 2022
United States USA41%4652024, 2022
Chile CHL40.5%4122024, 2022
Saudi Arabia SAU40.1%3892024, 2022
Panama PAN37.7%3572024, 2022
West Bank and Gaza PSE37.4%3662024, 2022
Mexico MEX37.4%3952024, 2022
Argentina ARG37.2%3782024, 2022
Brunei Darussalam BRN37.1%4422024, 2022
Georgia GEO35.7%3902024, 2022
Jordan JOR35.4%3612024, 2022
Jamaica JAM35.2%3772024, 2022
Uruguay URY34.9%4092024, 2022
Paraguay PRY34.7%3382024, 2022
New Zealand NZL34%4792024, 2022

World Health Organization, Global Health Observatory
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

Adult obesity

Prevalence of obesity among adults, age-standardised

World Health Organization · via Our World in Data · CC BY-NC-SA 4.0 · updated annual

Adults with a body mass index (weight compared with height) over 30. Adjusted to one age mix, so an older country and a younger one can be compared fairly. Estimated with a statistical model from surveys. It rises with income across the poorer half of the world, then stops rising across the richer half. Adjusting for GDP assumes a straight-line link, so it cannot capture that bend.

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 17,292 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated V-Dem v16; V-Party v2. How the country data works · explore Adult obesity and PISA maths

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

More links with Adult obesity or PISA maths