Contraceptive use (any method) vs. Religion very important
Holds up 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 81 countries, Contraceptive use (any method) and Religion very important rise and fall together at r = -0.54 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.39 (q = 0.012, 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.
Comparing countries across the middle half of religion very important, 19.7% to 82.9% of respondents, contraceptive use (any method) is 18.4% lower at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 15%.
Link before adjusting (r)-0.540p = 2.0e-7 · 81 countries
After adjusting for national income-0.389p = 0.000 · likely range [-0.56, -0.19]
p, allowing for regions0.006standard error 0.095 · 7 regions
Check for luck (q)0.012across 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 (any method) · %link with income +0.56 · moderate
Religion very important · % of respondentslink with income -0.66 · high
“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 | -0.540 | 2.0e-7 | 81 |
| By rank (Spearman), not adjusted | -0.541 | 1.8e-7 | 81 |
| Standard (Pearson), adjusted for national income | -0.389 | 0.000 | 81 |
| By rank (Spearman), adjusted for national income | -0.389 | 0.000 | 81 |
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 81 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: +0.150 (a minus sign means it grew).
How solid is it?
Leaving out one country at a time, r ranges from -0.429 (without HTI) to -0.323 (without QAT). 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: QAT (+0.067).
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 | 12 | -0.49 | |
| Europe & Central Asia | 32 | -0.49 | |
| Latin America & Caribbean | 12 | -0.16 |
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 | 27 | -0.18 | |
| Middle third | 27 | -0.50 | |
| Richest third | 27 | -0.73 |
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 | 44 | -0.33 | |
| Muslims | 27 | -0.16 |
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.
| n | r | ||
|---|---|---|---|
| Never a European colony | 15 | -0.06 | |
| United Kingdom | 20 | -0.56 |
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 = -0.320 after dropping 4 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 respondents | Years | |
|---|---|---|---|
| Finland FIN | 85.5% | 11% | 2015, 2022 |
| China CHN | 84.5% | 3.25% | 2017, 2022 |
| Korea, Rep. KOR | 84.2% | 10.3% | 2021, 2022 |
| Colombia COL | 81% | 58.4% | 2015, 2022 |
| Nicaragua NIC | 80.4% | 60% | 2012, 2022 |
| Germany DEU | 80.3% | 13.5% | 2011, 2022 |
| Brazil BRA | 80.2% | 45.1% | 2013, 2022 |
| France FRA | 78.4% | 14.3% | 2010, 2022 |
| Ecuador ECU | 77.9% | 53.6% | 2018, 2022 |
| Iran, Islamic Rep. IRN | 77.4% | 70.5% | 2010, 2022 |
| Peru PER | 77.3% | 44.6% | 2023, 2022 |
| Chile CHL | 76.3% | 20.7% | 2016, 2022 |
| United Kingdom GBR | 76.1% | 15.6% | 2012, 2022 |
| Estonia EST | 75.1% | 6.54% | 2014, 2022 |
| United States USA | 73.9% | 37.1% | 2019, 2022 |
World Bank, World Development Indicators
Haerpfer, C. et al., World Values Survey; EVS, European Values Study
Sources
Contraceptive use (any method)
Contraceptive prevalence, any method (% of married women ages 15-49)
World Bank · CC BY 4.0 · updated quarterly
The share of married women aged 15 to 49 who use any form of birth control, including traditional ones such as withdrawal, from national surveys. Only married women (and women living with a partner) are counted. Most countries have a survey only every few years.
Religion very important
Share saying religion is very important in their life
World Values Survey Association and European Values Study · via Our World in Data · Free for non-commercial use with attribution · updated irregular (survey waves, roughly every 5 years)
The strongest of four answers. The others are "rather", "not very" and "not at all" important. Thinking religion is important is different from attending services, and the gap between them is the interesting part. The United States reports high importance while attendance falls. Several Catholic countries show the reverse. No "better" direction is set, for the same reason as attendance. The survey runs in waves, not every year.
How this was computed
Data used: most recent value in 2010-2025; values come from 2010–2023. 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 (any method) and Religion very important
This page shows that two measures go together. It does not show that Contraceptive use (any method) changes Religion very important, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.
More links with Contraceptive use (any method) or Religion very important
- Frequent prayer vs Religion very important before +0.91 → after adjusting +0.85
- Religion very important vs Religious attendance before +0.84 → after adjusting +0.71
- Confidence in religious institutions vs Religion very important before +0.73 → after adjusting +0.62
- Religion very important vs Suicide rate before -0.65 → after adjusting -0.56
- PISA maths vs Religion very important before -0.73 → after adjusting -0.56
- Contraceptive use (any method) vs Fertility rate before -0.73 → after adjusting -0.56
- PISA science vs Religion very important before -0.73 → after adjusting -0.56
- PISA reading vs Religion very important before -0.73 → after adjusting -0.55