placestats

Contraceptive use (modern methods) vs. Religiously unaffiliated

Fades after adjusting for income

A country is not a person. Countries where more people are counted as belonging to this group also tend to differ on the other measure, and that is all. It does not follow that the people in the group are the people with the different score. Making that leap is called the ecological fallacy: reading a pattern across places as a fact about individual people. It is the most common misuse of this kind of data. Religion also varies strongly with region, history and national income, so much of what looks religious here is really those. That is what the adjusted figures are for. The religion shares are estimates for two years only, and the survey questions are asked in rounds that can be ten years apart.

Across 143 countries, Contraceptive use (modern methods) and Religiously unaffiliated rise and fall together at r = +0.50 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) leaves r = +0.37, which could easily be chance (q = 0.15, allowing for the many pairs tested, and allowing for countries in the same region being alike). Caution: direction is not consistent across regions.

Comparing countries across the middle half of religiously unaffiliated, 0.135% to 10.3% of population, contraceptive use (modern methods) is 6.86% higher at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 5%.

Link before adjusting (r)+0.505p = 1.3e-10 · 143 countries
After adjusting for national income+0.374p = 4.5e-6 · likely range [+0.22, +0.51]
p, allowing for regions0.040standard error 0.143 · 7 regions
Check for luck (q)0.152across 14,952 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.

Contraceptive use (modern methods) · %link with income +0.46 · moderate
Religiously unaffiliated · % of populationlink with income +0.51 · moderate

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

Every country as a dot

Contraceptive use (modern methods) · % →Religiously unaffiliated · % of population →0.9%81.6%0%89.6%Afghanistan: 19.8%, 0.00846% of populationAngola: 12.5%, 6.11% of populationAlbania: 3.7%, 7.65% of populationArgentina: 67.2%, 9.23% of populationArmenia: 28%, 1.18% of populationAustralia: 64.7%, 42.3% of populationAustria: 63%, 22.4% of populationAzerbaijan: 13.9%, 4.76% of populationBurundi: 22.9%, 1.25% of populationBelgium: 65.4%, 39% of populationBenin: 16.9%, 4.89% of populationBurkina Faso: 31.3%, 0.576% of populationBangladesh: 54.7%, 0% of populationBosnia and Herzegovina: 12.1%, 1.05% of populationBelarus: 45.9%, 13.8% of populationBelize: 48.5%, 15.6% of populationBolivia: 45.1%, 9.55% of populationBrazil: 77.7%, 13.5% of populationBarbados: 55.4%, 20.1% of populationBhutan: 65.4%, 0.0437% of populationCentral African Republic: 14.4%, 0.452% of populationSwitzerland: 67.3%, 30.8% of populationChile: 69.8%, 30.3% of populationChina: 80.5%, 89.6% of populationCote d'Ivoire: 25.2%, 5.56% of populationCameroon: 15.4%, 2.08% of populationCongo, Dem. Rep.: 17.6%, 1.18% of populationCongo, Rep.: 18.3%, 5.2% of populationColombia: 75.9%, 9.94% of populationComoros: 8.6%, 0.13% of populationCabo Verde: 54.6%, 20.6% of populationCosta Rica: 70%, 10.1% of populationGermany: 80.2%, 36.1% of populationDjibouti: 18%, 1.1% of populationDominican Republic: 62%, 19.6% of populationAlgeria: 44.9%, 1.27% of populationEcuador: 72.4%, 8.39% of populationEgypt, Arab Rep.: 56.9%, 0.00465% of populationSpain: 59.9%, 26.4% of populationEstonia: 60.9%, 43.6% of populationEthiopia: 34.6%, 0.0623% of populationFinland: 81.6%, 25% of populationFiji: 31.2%, 0.251% of populationFrance: 72.7%, 42.6% of populationGabon: 17.3%, 5.76% of populationUnited Kingdom: 71.1%, 40.2% of populationGeorgia: 31.2%, 0.988% of populationGhana: 27.8%, 1.07% of populationGuinea: 10.6%, 1.32% of populationGambia, The: 17.1%, 0.0179% of populationGuinea-Bissau: 20.2%, 11.6% of populationEquatorial Guinea: 9.6%, 4.99% of populationGuatemala: 48.9%, 6.02% of populationGuyana: 28.6%, 2.91% of populationHong Kong SAR, China: 64.5%, 71.4% of populationHonduras: 66.5%, 9.74% of populationHaiti: 31.8%, 9.43% of populationIndonesia: 51.6%, 0.092% of populationIndia: 56.4%, 0.00326% of populationIreland: 70.9%, 15.6% of populationIran, Islamic Rep.: 57%, 0.00005% of populationIraq: 36.1%, 0.000799% of populationItaly: 51.8%, 13.3% of populationJamaica: 53.2%, 23.7% of populationJordan: 38.4%, 0.0474% of populationJapan: 52.8%, 57.5% of populationKazakhstan: 50.1%, 2.53% of populationKenya: 56.9%, 1.6% of populationKyrgyz Republic: 37.8%, 1.17% of populationCambodia: 44.7%, 0.079% of populationKiribati: 27.3%, 0.1% of populationKorea, Rep.: 67.6%, 48.3% of populationLao PDR: 51%, 0.0528% of populationLiberia: 23.9%, 1.07% of populationLibya: 16.3%, 0.0494% of populationSt. Lucia: 52.4%, 5.9% of populationSri Lanka: 53.6%, 0.0699% of populationLesotho: 65.3%, 1.66% of populationMorocco: 59.1%, 0.131% of populationMoldova: 43.9%, 0.234% of populationMadagascar: 42.7%, 22.3% of populationMaldives: 14.9%, 0.068% of populationMexico: 69.1%, 10.6% of populationNorth Macedonia: 14%, 0.516% of populationMali: 16.4%, 2.53% of populationMyanmar: 51.3%, 0.0586% of populationMontenegro: 11.6%, 1.14% of populationMongolia: 45.2%, 40.8% of populationMozambique: 25.4%, 14.3% of populationMauritania: 12.8%, 0.107% of populationMauritius: 31.1%, 0.753% of populationMalawi: 64.7%, 0.941% of populationMalaysia: 34.5%, 0.845% of populationNamibia: 55.3%, 5.63% of populationNiger: 13.9%, 1.22% of populationNigeria: 18.2%, 0.379% of populationNicaragua: 77.4%, 13.3% of populationNepal: 42.7%, 0.00129% of populationOman: 18.8%, 0.14% of populationPakistan: 25%, 0.0127% of populationPanama: 46.9%, 6.21% of populationPeru: 57.9%, 5.11% of populationPhilippines: 41.8%, 0.0411% of populationPapua New Guinea: 30.5%, 0.311% of populationPoland: 50.7%, 8.65% of populationParaguay: 66.4%, 4.25% of populationWest Bank and Gaza: 42.8%, 0% of populationQatar: 34.3%, 0.274% of populationRussian Federation: 55%, 20.2% of populationRwanda: 58.4%, 1.01% of populationSaudi Arabia: 32.9%, 0.112% of populationSudan: 12%, 0.563% of populationSenegal: 25.6%, 0.0207% of populationSolomon Islands: 24.3%, 0.328% of populationSierra Leone: 20.9%, 0.012% of populationEl Salvador: 52.1%, 11.9% of populationSomalia, Fed. Rep.: 0.9%, 0.0161% of populationSerbia: 21.3%, 4.01% of populationSao Tome and Principe: 46%, 9.69% of populationSuriname: 38.7%, 8.11% of populationEswatini: 57%, 6.16% of populationChad: 6.7%, 3.13% of populationTogo: 21.4%, 8.01% of populationThailand: 70.7%, 0.0126% of populationTajikistan: 27.1%, 0.0746% of populationTurkmenistan: 47.3%, 0.0719% of populationTimor-Leste: 24.1%, 0.0639% of populationTonga: 25.2%, 0.581% of populationTrinidad and Tobago: 30.5%, 2.45% of populationTunisia: 48.4%, 0.441% of populationTurkiye: 48.9%, 2.53% of populationTanzania: 31.1%, 3.48% of populationUganda: 38%, 0.0949% of populationUkraine: 47.6%, 15.1% of populationUnited States: 66.1%, 29.7% of populationUzbekistan: 56.4%, 0.552% of populationViet Nam: 59.8%, 67.7% of populationVanuatu: 37.1%, 1.37% of populationSamoa: 15.8%, 0.0642% of populationKosovo: 9.4%, 0.139% of populationSouth Africa: 54%, 3.12% of populationZambia: 47.5%, 0.0598% of populationZimbabwe: 65.8%, 10.5% of populationBTNCHNCOMHKGMWISOMTHAVNMXKX

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted+0.5051.3e-10143
By rank (Spearman), not adjusted+0.4521.4e-8143
Standard (Pearson), adjusted for national income+0.3744.5e-6143
By rank (Spearman), adjusted for national income+0.3170.000143

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 143 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: +0.130 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from +0.348 (without CHN) to +0.387 (without JPN). 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: CHN (-0.026).

Fragile: this link may not hold up.
  • direction is not consistent across regions

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 & Pacific22+0.44
Europe & Central Asia31+0.56
Latin America & Caribbean24+0.34
Middle East, North Africa, Afghanistan & Pakistan15-0.08
Sub-Saharan Africa44+0.25

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 third48+0.23
Middle third47+0.19
Richest third48+0.58

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
Christians84+0.45
Muslims44-0.23

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
France23+0.46
Never a European colony21+0.52
Spain18+0.36
United Kingdom44+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 = +0.372 after dropping 16 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 0years. So a link here can’t come from anything about a country that stays the same, such as its history, geography, institutions or culture.

Not enough history inside each country to look at this over time. That needs countries measured for several years in a row, and at least one of these measures is measured too rarely.

The data


%
% of population		Years
Finland FIN81.6%25%2015, 2020
China CHN80.5%89.6%2017, 2020
Germany DEU80.2%36.1%2011, 2020
Brazil BRA77.7%13.5%2013, 2020
Nicaragua NIC77.4%13.3%2012, 2020
Colombia COL75.9%9.94%2015, 2020
France FRA72.7%42.6%2010, 2020
Ecuador ECU72.4%8.39%2018, 2020
United Kingdom GBR71.1%40.2%2012, 2020
Ireland IRL70.9%15.6%2010, 2020
Thailand THA70.7%0.0126%2022, 2020
Costa Rica CRI70%10.1%2018, 2020
Chile CHL69.8%30.3%2016, 2020
Mexico MEX69.1%10.6%2023, 2020
Korea, Rep. KOR67.6%48.3%2021, 2020

World Bank, World Development Indicators
Pew Research Center, Religious Composition by Country, 2010-2020. Pew Research Center bears no responsibility for the analyses or interpretations of the data presented here.
One of these measures is published under a licence that forbids changes. Values are shown exactly as published and must not be republished in a changed or rescaled form.

Sources

Contraceptive use (modern methods)

Contraceptive prevalence, any modern method (% of married women ages 15-49)

World Bank · CC BY 4.0 · updated quarterly

The same survey share as contraceptive use by any method, counting only modern methods: the pill, condoms, IUDs, implants, injections and sterilisation. Most countries have a survey only every few years.

Religiously unaffiliated

Share of the population religiously unaffiliated

Pew Research Center · via Our World in Data · Pew Research Center terms of use, excerpts with attribution · updated decennial · comparable from 2010 only

People who belong to no religion: atheists, agnostics and those who say "nothing in particular". Pew estimated it from censuses and surveys for 2010 and 2020. Belonging is a third thing, beside the attendance and importance measures already here. A country can be almost all affiliated and rarely attend, as much of Europe is. With only two years, nothing here shows a trend. No "better" direction is set.

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 14,952 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Contraceptive use (modern methods) and Religiously unaffiliated

This page shows that two measures go together. It does not show that Contraceptive use (modern methods) changes Religiously unaffiliated, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.

More links with Contraceptive use (modern methods) or Religiously unaffiliated