Do Independent opposition and Marriage rate (UN) go together across countries?

Across 86 countries the link before adjusting for anything is r = -0.42, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.39.

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

Comparing each country only with itself across 2013-2024, and setting aside what happened worldwide in each year, the link is +0.020 (82 countries, 879 country-years). Using year-to-year changes, it is +0.023.

Does Independent opposition cause Marriage rate (UN)?

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.

Independent opposition vs. Marriage rate (UN)

Holds up after adjusting for income

Across 86 countries, Independent opposition and Marriage rate (UN) rise and fall together at r = -0.42 (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 = -0.34, q = 0.017, allowing for the many pairs tested).

Comparing countries across the middle half of marriage rate (UN), 3.81 to 5.99 marriages per 1,000 people, independent opposition is worse by 0.805 points at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 0.586 points.

Link before adjusting (r)-0.422p = 5.2e-5 · 86 countries

After adjusting for national income-0.341p = 0.001 · likely range [-0.52, -0.14]

p, allowing for regions0.000standard error 0.048 · 7 regions

Check for luck (q)0.017across 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.

Independent opposition · score (higher = more independent)link with income +0.45 · moderate

Marriage rate (UN) · marriages per 1,000 peoplelink with income -0.21 · independent

“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	-0.422	5.2e-5	86
By rank (Spearman), not adjusted	-0.388	0.000	86
Standard (Pearson), adjusted for national income	-0.341	0.001	86
By rank (Spearman), adjusted for national income	-0.280	0.010	86

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 86 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: +0.081 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.389 (without KWT) to -0.286 (without RUS). 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: RUS (+0.055).

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
Europe & Central Asia	47	-0.33
Latin America & Caribbean	15	-0.08

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	29	-0.27
Middle third	28	-0.39
Richest third	29	-0.33

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	58	-0.18
Muslims	15	-0.15

By last European coloniser

	n	r
Never a European colony	12	-0.52
United Kingdom	19	-0.01

By official ideology

	n	r
Nationalist	12	-0.51
No strong official ideology	65	-0.27

By party system

	n	r
No parties banned	72	-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 = -0.372 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 12years. 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 = +0.020, 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 independent opposition moved did not tend to see their marriage rate (UN) move with it.

Across countries (adjusted)-0.341for comparison

Within countries+0.109each country vs itself

…and vs the same year elsewhere+0.020q = 0.921 · 82 countries

Year-on-year changes+0.023q = 0.805

Read with care.

Almost all of the second indicator's variation is between countries, so the within-country estimate rests on a small part of the data.

879 country-years (one country in one year), 82 countries, 2013–2024, about 11 years each on average. Share of the variation that happens within countries over time: 17% for Independent opposition, 4% for Marriage rate (UN). 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): +0.020. 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 (+0.15 at lag -4) is higher than the same-year one by 0.13. That gap is not a finding. It is the largest of 19 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

	score (higher = more independent)	marriages per 1,000 people	Years
Chile CHL	3.13	3.04	2025, 2024
Ireland IRL	3.01	3.8	2025, 2024
Uruguay URY	2.96	2.78	2025, 2022
Netherlands NLD	2.86	3.83	2025, 2024
Belgium BEL	2.85	3.96	2025, 2023
Latvia LVA	2.84	5.45	2025, 2024
Slovak Republic SVK	2.84	4.88	2025, 2023
Denmark DNK	2.83	5.51	2025, 2024
New Zealand NZL	2.77	3.41	2025, 2024
Sweden SWE	2.77	4.25	2025, 2024
Korea, Rep. KOR	2.76	4.36	2025, 2024
Spain ESP	2.74	3.57	2025, 2023
Italy ITA	2.73	3.12	2025, 2023
Austria AUT	2.73	5	2025, 2024
Switzerland CHE	2.72	4.21	2025, 2023

Coppedge, M. et al., V-Dem Dataset v16, Varieties of Democracy (V-Dem) Project; Lindberg, S. I. et al., Varieties of Party Identity and Organization (V-Party) Dataset. Read from the V-Dem Institute's vdemdata package.
United Nations Statistics Division, Demographic Yearbook, 2017 to 2024 editions: tables of marriages and crude marriage rates, of divorces and crude divorce rates, by urban/rural residence, and of legally induced abortions. Women aged 15 to 49 from the World Bank, World Development Indicators (CC BY 4.0).

Sources

Independent opposition

Opposition parties' independence from the ruling regime

V-Dem Institute, University of Gothenburg · CC BY-SA 4.0 · updated annual (V-Dem); V-Party per election, to 2019

Are opposition parties really independent, or picked or bought by the people in power? Experts answer from 0 ("opposition parties are not allowed") to 4 ("all opposition parties are independent"). V-Dem turns the answers into a score of about -4 to +4. A part of V-Dem's freedom of association index.

Marriage rate (UN)

Crude marriage rate, countries with complete registration

United Nations Statistics Division · UNdata terms of use · updated annual (each edition covers the latest five years)

Marriages registered in the year per 1,000 people, from each country's civil register, as published in the UN Demographic Yearbook. Only countries whose register the UN rates as at least 90% complete are included. That leaves out most of Africa and much of South Asia, where many marriages are religious or customary and never registered, so the countries here lean toward places with strong record-keeping. Countries whose figures include visitors' weddings (Seychelles, about 30 per 1,000, and the Bahamas) are left out, since they show a wedding industry rather than how often residents marry. So is Equatorial Guinea, whose register is far too thin to be complete. Each yearly edition covers five years; where they overlap, the newest is used, since countries revise. Where both exist it matches the OECD series almost exactly (r = 0.998), so the two are treated as one measure, not two findings. The low points in 2020 are the pandemic. A few small island territories, such as the Turks and Caicos Islands (11 to 16 per 1,000), probably count visitors' weddings without saying so. No "better" direction is set: it describes how people live.

How this was computed

Data used: most recent value in 2010-2025; values come from 2013–2025. 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 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 Independent opposition and Marriage rate (UN)

This page shows that two measures go together. It does not show that Independent opposition changes Marriage rate (UN), or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.