Do Health coverage index and Road traffic deaths go together across countries?

Across 183 countries the link before adjusting for anything is r = -0.61, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives -0.66.

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

Comparing each country only with itself across 2000-2019, and setting aside what happened worldwide in each year, the link is +0.135 (183 countries, 3,660 country-years). Using year-to-year changes, it is +0.027.

Does Health coverage index cause Road traffic deaths?

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.

Health coverage index vs. Road traffic deaths

Fades after adjusting for income

Across 183 countries, Health coverage index and Road traffic deaths rise and fall together at r = -0.61 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.12, which could easily be chance (q = 0.38, 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. Caution: direction is not consistent across regions.

Comparing countries across the middle half of road traffic deaths, 7.6 to 23.7 per 100,000 population, health coverage index is worse by 14.3 points at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 1.9 points.

Link before adjusting (r)-0.613p = 3.1e-20 · 183 countries

After adjusting for national income-0.124p = 0.094 · likely range [-0.27, +0.02]

p, allowing for regions0.051standard error 0.051 · 7 regions

Check for luck (q)0.377across 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.

Health coverage index · index, 0 to 100link with income +0.88 · proxy

Road traffic deaths · per 100,000 populationlink with income -0.71 · high

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	-0.613	3.1e-20	183
By rank (Spearman), not adjusted	-0.656	7.0e-24	183
Standard (Pearson), adjusted for national income	-0.124	0.094	183
By rank (Spearman), adjusted for national income	-0.091	0.221	183

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 183 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: +0.488 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.151 (without PNG) to -0.101 (without FSM). 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: PNG (-0.027).

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.

	n	r
East Asia & Pacific	27	+0.16
Europe & Central Asia	50	-0.19
Latin America & Caribbean	30	-0.27
Middle East, North Africa, Afghanistan & Pakistan	22	-0.08
Sub-Saharan Africa	46	+0.09

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	61	-0.23
Middle third	61	-0.12
Richest third	61	-0.13

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	108	-0.11
Muslims	49	-0.30

By last european coloniser

	n	r
France	25	-0.47
Never a European colony	21	-0.07
Spain	20	-0.38
United Kingdom	60	+0.02

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 1 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 20years. 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 shows up within countries over time (r = +0.135) but mostly disappears in year-to-year changes (r = +0.027). That points to slow trends particular to each country, not the two measures moving together from year to year.

Across countries (adjusted)-0.124for comparison

Within countries-0.164each country vs itself

…and vs the same year elsewhere+0.135q = 0.026 · 183 countries

Year-on-year changes+0.027q = 0.172

The direction flips. Comparing each country only with itself gives -0.16. Also taking out what happened to the whole world each year gives +0.13. 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 the second indicator's variation is between countries, so the within-country estimate rests on a small part of the data.

3,660 country-years (one country in one year), 183 countries, 2000–2019, about 20 years each on average. Share of the variation that happens within countries over time: 13% for Health coverage index, 7% for Road traffic deaths. 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): +0.135. 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 data

	index, 0 to 100	per 100,000 population	Years
Canada CAN	92	5.3	2023, 2019
Iceland ISL	90	2	2023, 2019
New Zealand NZL	89	9.6	2023, 2019
Norway NOR	89	2.1	2023, 2019
Australia AUS	89	4.9	2023, 2019
United States USA	88	12.7	2023, 2019
Singapore SGP	88	2.1	2023, 2019
Korea, Rep. KOR	88	8.6	2023, 2019
United Kingdom GBR	88	3.2	2023, 2019
Germany DEU	87	3.8	2023, 2019
Switzerland CHE	87	2.2	2023, 2019
Japan JPN	86	3.6	2023, 2019
Finland FIN	86	3.9	2023, 2019
Belgium BEL	86	5.8	2023, 2019
Uruguay URY	85	14.8	2023, 2019

World Health Organization, Global Health Observatory
World Bank, World Development Indicators

Sources

Health coverage index

Universal health coverage service coverage index

World Health Organization · via Our World in Data · CC BY-NC-SA 4.0 · updated annual

Fourteen "tracer" measures of basic health services, combined by WHO into one index. They include vaccination, care during pregnancy, treatment of tuberculosis and HIV, and hospital beds and staff. Several of those measures are on the site on their own. So a link with any of them is partly the index matching a part of itself.

Road traffic deaths

Mortality from road traffic injury (per 100,000 population)

World Health Organization · 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 2013–2023. 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 12,497 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Health coverage index and Road traffic deaths

This page shows that two measures go together. It does not show that Health coverage index changes Road traffic deaths, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.