Do Adolescent fertility and Researchers go together across countries?

Across 131 countries the link before adjusting for anything is r = -0.57, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.85.

Does the link hold within countries over time, not just across countries?

Comparing each country only with itself across 1996-2024, and setting aside what happened worldwide in each year, the link is +0.222 (103 countries, 1,875 country-years). Using year-to-year changes, it is +0.098.

Does Adolescent fertility cause Researchers?

This analysis cannot answer that. It shows only that the two go together. A link between two country measures, adjusted or not, does not show that either one changes the other. Country figures also say nothing about individual people.

Adolescent fertility vs. Researchers

Fades after adjusting for income

Across 131 countries, Adolescent fertility and Researchers rise and fall together at r = -0.57 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.03, which could easily be chance (q = 0.88, 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 adolescent fertility, 5.8 to 53.5 births per 1,000 women aged 15-19, researchers is worse by 1,829 per million people at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 116 per million people.

Link before adjusting (r)-0.568p = 1.4e-12 · 131 countries

After adjusting for national income-0.029p = 0.744 · likely range [-0.20, +0.14]

p, allowing for regions0.785standard error 0.101 · 7 regions

Check for luck (q)0.877across 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.

Adolescent fertility · births per 1,000 women aged 15-19link with income -0.81 · proxy

Researchers · per million peoplelink with income +0.85 · 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

best-fit line line after adjusting

Four ways to measure the link

Method	r	p	Countries
Standard (Pearson), not adjusted	-0.568	1.4e-12	131
By rank (Spearman), not adjusted	-0.853	2.7e-38	131
Standard (Pearson), adjusted for national income	-0.029	0.744	131
By rank (Spearman), adjusted for national income	-0.458	4.1e-8	131

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 131 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: +0.539 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.051 (without MOZ) to -0.000 (without BDI). 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: BDI (+0.029).

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.

	n	r
East Asia & Pacific	18	-0.13
Europe & Central Asia	45	-0.25
Latin America & Caribbean	17	-0.52
Middle East, North Africa, Afghanistan & Pakistan	17	-0.24
Sub-Saharan Africa	29	-0.36

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.

	n	r
Poorest third	44	-0.42
Middle third	43	-0.28
Richest third	44	-0.44

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.

	n	r
Christians	80	-0.15
Muslims	32	-0.25

By last european coloniser

	n	r
France	13	-0.24
Never a European colony	15	-0.15
Spain	16	-0.71
United Kingdom	36	+0.09

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 = -0.136 after dropping 11 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.

The link also shows up within countries over time (r = +0.222). It holds even when looking only at changes from one year to the next (r = +0.098). This is the strongest kind of evidence available here: it holds when each country is compared only with itself, and it is not just a product of shared trends.

Across countries (adjusted)-0.029for comparison

Within countries-0.276each country vs itself

…and vs the same year elsewhere+0.222q = 0.010 · 103 countries

Year-on-year changes+0.098q = 0.002

The direction flips. Comparing each country only with itself gives -0.28. Also taking out what happened to the whole world each year gives +0.22. 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 this indicator's variation is between countries, not within them, so the within-country estimate rests on a small part of the data.

1,875 country-years (one country in one year), 103 countries, 1996–2024, about 18 years each on average. Share of the variation that happens within countries over time: 5% for Adolescent fertility, 14% for Researchers. 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

Same year (lag 0): +0.222. 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.

This curve peaks at the edge of the window (lag -10), so it is still drifting where the search stops. That pattern usually reflects a slow trend left over in the data, not a link with real timing. The peak value should not be read as the “true” link at the right lag.

The data

	births per 1,000 women aged 15-19	per million people	Years
Mozambique MOZ	152	44.4	2024, 2015
Niger NER	142	26.9	2024, 2013
Angola AGO	139	18.9	2024, 2016
Mali MLI	136	26	2024, 2023
Chad TCD	132	56.7	2024, 2016
Madagascar MDG	129	32.9	2024, 2018
Malawi MWI	113	25.2	2024, 2019
Tanzania TZA	113	19.3	2024, 2013
Congo, Rep. COG	108	127	2024, 2022
Congo, Dem. Rep. COD	105	10.1	2024, 2015
Uganda UGA	105	81.3	2024, 2023
Zimbabwe ZWE	95.5	95.1	2024, 2012
Burkina Faso BFA	85.5	46.6	2024, 2010
Nigeria NGA	84	22.1	2024, 2019
Honduras HND	81.3	188	2024, 2019

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

Sources

Adolescent fertility

Adolescent fertility rate (births per 1,000 women ages 15-19)

UN Population Division, World Population Prospects · CC BY 4.0 · updated quarterly

Researchers

Researchers in R&D (per million people)

UNESCO Institute for Statistics · CC BY 4.0 · updated quarterly

Researchers counted as full-time equivalents (two half-time researchers count as one), from national research surveys that many countries run only now and then. So coverage is thin outside the OECD.

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 7 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 Adolescent fertility and Researchers

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