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Public social spending vs. Pupil-teacher ratio

Holds up after adjusting for income

Across 40 countries, Public social spending and Pupil-teacher ratio rise and fall together at r = -0.45 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.24 (q = 0.018, allowing for the many pairs tested). Much of the first figure is that both measures rise with national income, but a weak negative link remains. Caution: leave-one-out range spans 0.25 in r.

Comparing countries across the middle half of public social spending, 16.8% to 24.7% of GDP, pupil-teacher ratio is better by 2.28 pupils per teacher at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 1.15 pupils per teacher.

Link before adjusting (r)-0.450p = 0.004 · 40 countries
After adjusting for national income-0.242p = 0.138 · likely range [-0.52, +0.08]
p, allowing for regions0.001standard error 0.026 · 5 regions
Check for luck (q)0.018across 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.

Public social spending · % of GDPlink with income +0.44 · moderate
Pupil-teacher ratio · pupils per teacherlink with income -0.83 · proxy

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

Every country as a dot

Public social spending · % of GDP →Pupil-teacher ratio · pupils per teacher →7.55%31.6%8.326.6Austria: 31.6% of GDP, 10 pupils per teacherBelgium: 28.6% of GDP, 11.3 pupils per teacherBulgaria: 20.5% of GDP, 15.2 pupils per teacherSwitzerland: 16% of GDP, 9.93 pupils per teacherChile: 12.9% of GDP, 17.8 pupils per teacherColombia: 14.1% of GDP, 23.3 pupils per teacherCosta Rica: 12.6% of GDP, 12.2 pupils per teacherCzechia: 22.1% of GDP, 18.9 pupils per teacherGermany: 27.9% of GDP, 12.3 pupils per teacherDenmark: 26.4% of GDP, 10.7 pupils per teacherSpain: 25.9% of GDP, 13.1 pupils per teacherEstonia: 17.2% of GDP, 11.3 pupils per teacherFinland: 31.4% of GDP, 13.7 pupils per teacherFrance: 30.6% of GDP, 18.2 pupils per teacherUnited Kingdom: 23% of GDP, 15.1 pupils per teacherGreece: 23.7% of GDP, 9.38 pupils per teacherCroatia: 22.5% of GDP, 13.5 pupils per teacherHungary: 18% of GDP, 10.8 pupils per teacherIreland: 14.4% of GDP, 16.1 pupils per teacherIceland: 19.2% of GDP, 10.1 pupils per teacherIsrael: 16.3% of GDP, 12.1 pupils per teacherItaly: 27.6% of GDP, 11.5 pupils per teacherJapan: 24.7% of GDP, 15.7 pupils per teacherKorea, Rep.: 15.3% of GDP, 16.3 pupils per teacherLithuania: 16.9% of GDP, 13.5 pupils per teacherLuxembourg: 24% of GDP, 8.3 pupils per teacherLatvia: 19.7% of GDP, 11.5 pupils per teacherMexico: 10% of GDP, 26.6 pupils per teacherNetherlands: 18.9% of GDP, 11.8 pupils per teacherNorway: 24.1% of GDP, 8.59 pupils per teacherNew Zealand: 24.6% of GDP, 14.9 pupils per teacherPeru: 7.55% of GDP, 17.4 pupils per teacherPoland: 23.1% of GDP, 10.2 pupils per teacherPortugal: 24.1% of GDP, 12.4 pupils per teacherRomania: 17.6% of GDP, 19.3 pupils per teacherSlovak Republic: 19.3% of GDP, 15.5 pupils per teacherSlovenia: 23% of GDP, 13.8 pupils per teacherSweden: 26.1% of GDP, 12.2 pupils per teacherTurkiye: 10.4% of GDP, 17 pupils per teacherUnited States: 19.8% of GDP, 14.2 pupils per teacherAUTBELCHECOLCRICZEFINFRALUXMEXPER

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted-0.4500.00440
By rank (Spearman), not adjusted-0.3740.01740
Standard (Pearson), adjusted for national income-0.2420.13840
By rank (Spearman), adjusted for national income-0.2040.21440

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 40 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: +0.208 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.336 (without FRA) to -0.088 (without IRL). 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: IRL (+0.154).

Fragile: this link may not hold up.
  • leave-one-out range spans 0.25 in r

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
Europe & Central Asia30-0.19

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 third14-0.26
Middle third13+0.08
Richest third13-0.31

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
Christians33-0.26

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 = -0.185 after dropping 2 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 29years. 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 = -0.046, 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 public social spending moved did not tend to see their pupil-teacher ratio move with it.

Across countries (adjusted)-0.242for comparison
Within countries-0.353each country vs itself
…and vs the same year elsewhere-0.046q = 0.765 · 41 countries
Year-on-year changes-0.076q = 0.335
Read with care.
  • 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.

682 country-years (one country in one year), 41 countries, 1990–2018, about 17 years each on average. Share of the variation that happens within countries over time: 12% for Public social spending, 19% 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

0.40−0.4-100+10years Pupil-teacher ratio trails Public social spending →lag -10: r = -0.282 (n = 639)lag -9: r = -0.312 (n = 666)lag -8: r = -0.331 (n = 686)lag -7: r = -0.308 (n = 718)lag -6: r = -0.277 (n = 726)lag -5: r = -0.241 (n = 731)lag -4: r = -0.232 (n = 724)lag -3: r = -0.205 (n = 715)lag -2: r = -0.161 (n = 706)lag -1: r = -0.092 (n = 694)lag +0: r = -0.046 (n = 682)lag +1: r = 0.014 (n = 655)lag +2: r = 0.019 (n = 629)lag +3: r = 0.077 (n = 599)lag +4: r = 0.081 (n = 567)lag +5: r = 0.032 (n = 531)lag +6: r = 0.082 (n = 501)lag +7: r = 0.095 (n = 481)lag +8: r = 0.102 (n = 458)lag +9: r = 0.056 (n = 427)lag +10: r = 0.067 (n = 405)

Same year (lag 0): -0.046. 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 (-0.33 at lag -8) is higher than the same-year one by 0.28. 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 GDP
pupils per teacher		Years
Austria AUT31.6%102024, 2017
Finland FIN31.4%13.72024, 2017
France FRA30.6%18.22024, 2013
Belgium BEL28.6%11.32024, 2017
Germany DEU27.9%12.32024, 2017
Italy ITA27.6%11.52024, 2017
Denmark DNK26.4%10.72024, 2014
Sweden SWE26.1%12.22024, 2017
Spain ESP25.9%13.12024, 2017
Japan JPN24.7%15.72022, 2017
New Zealand NZL24.6%14.92022, 2017
Portugal PRT24.1%12.42024, 2017
Norway NOR24.1%8.592024, 2017
Luxembourg LUX24%8.32024, 2016
Greece GRC23.7%9.382024, 2017

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
World Bank, World Development Indicators

Sources

Public social spending

Public social expenditure

OECD · via Our World in Data · CC BY 4.0 (OECD terms and conditions) · updated annual, except the snapshots noted per indicator · comparable from 1980 only

All public social spending, as a share of GDP: pensions, health, family, unemployment, housing and the rest. The figures before 1980 are stitched together from older OECD tables and from Lindert's historical estimates, so they are left out. The OECD's social spending database (SOCX) itself starts in 1980. The four spending areas below are parts of this total and are flagged as such.

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 2012–2024. 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 Public social spending and Pupil-teacher ratio

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

More links with Public social spending or Pupil-teacher ratio