Do One-person households and Price level go together across countries?

Across 141 countries the link before adjusting for anything is r = +0.63, on a scale from -1 (opposite) to +1 (in step). A version that uses only each country's rank gives +0.62.

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

Comparing each country only with itself across 1990-2021, and setting aside what happened worldwide in each year, the link is -0.048 (56 countries, 406 country-years). Using year-to-year changes, it is —.

Does One-person households cause Price level?

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.

One-person households vs. Price level

Holds up after adjusting for income

Across 141 countries, One-person households and Price level rise and fall together at r = +0.63 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to +0.35 (q = 0.045, allowing for the many pairs tested). Much of the first figure is that both measures rise with national income, but a weak positive link remains.

Comparing countries across the middle half of price level, 0.336 to 0.672 ratio to the US, one-person households is 9.2% of households higher at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 5.04% of households.

Link before adjusting (r)+0.634p = 3.1e-17 · 141 countries

After adjusting for national income+0.352p = 2.0e-5 · likely range [+0.20, +0.49]

p, allowing for regions0.009standard error 0.094 · 7 regions

Check for luck (q)0.045across 18,622 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.

One-person households · % of householdslink with income +0.70 · high

Price level · ratio to the US (US = 1)link with income +0.72 · 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	+0.634	3.1e-17	141
By rank (Spearman), not adjusted	+0.623	1.6e-16	141
Standard (Pearson), adjusted for national income	+0.352	2.0e-5	141
By rank (Spearman), adjusted for national income	+0.272	0.001	141

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 141 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: +0.282 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from +0.332 (without BRN) to +0.396 (without BLR). 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: BLR (+0.044).

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	17	+0.50
Europe & Central Asia	39	+0.02
Latin America & Caribbean	25	+0.37
Sub-Saharan Africa	41	+0.15

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	47	+0.23
Middle third	47	+0.29
Richest third	47	+0.34

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	87	+0.20
Muslims	35	-0.09

By last European coloniser

	n	r
France	22	+0.34
Never a European colony	14	+0.64
Spain	16	-0.18
United Kingdom	40	+0.47

By official ideology

	n	r
Nationalist	21	+0.17
No strong official ideology	96	+0.40

By party system

	n	r
A few parties banned	24	+0.25
No parties banned	99	+0.34

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 = +0.339 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.

Loading…

Over time, within countries

Everything above compares countries with each other at one moment. This section compares each country only with itself over 32years. 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 = -0.048, 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 one-person households moved did not tend to see their price level move with it.

Across countries (adjusted)+0.352for comparison

Within countries-0.053each country vs itself

…and vs the same year elsewhere-0.048q = 0.483 · 56 countries

Year-on-year changes—q = —

406 country-years (one country in one year), 56 countries, 1990–2021, about 7 years each on average. Share of the variation that happens within countries over time: 27% for One-person households, 13% for Price level. 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): -0.048. 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 (+0.18 at lag -6) is higher than the same-year one by 0.13. That gap is not a finding. It is the largest of 21 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

	% of households	ratio to the US (US = 1)	Years
Latvia LVA	41.1%	0.672	2021, 2023
Finland FIN	41%	0.968	2010, 2023
Norway NOR	39.6%	0.971	2011, 2023
Belarus BLR	38%	0.271	2019, 2023
Germany DEU	37.3%	0.839	2011, 2023
Austria AUT	36.3%	0.87	2011, 2023
France FRA	35.5%	0.847	2015, 2023
Japan JPN	34.5%	0.793	2015, 2023
Bermuda BMU	34.1%	1.3	2016, 2023
Belgium BEL	34%	0.893	2011, 2023
Luxembourg LUX	33.3%	1.07	2011, 2023
Slovenia SVN	32.6%	0.706	2015, 2023
Czechia CZE	32.5%	0.701	2011, 2023
Hungary HUN	32.1%	0.592	2011, 2023
Korea, Rep. KOR	31.8%	0.728	2020, 2023

United Nations, Department of Economic and Social Affairs, Population Division (2022). Database on Household Size and Composition 2022.
Feenstra, Robert C., Robert Inklaar and Marcel P. Timmer (2015), "The Next Generation of the Penn World Table", American Economic Review, 105(10), 3150-3182, www.ggdc.net/pwt. Data: Penn World Table version 11.0, Groningen Growth and Development Centre, doi:10.34894/FABVLR.

Sources

One-person households

Share of one-person households

United Nations Department of Economic and Social Affairs, Population Division · via Our World in Data · CC BY 3.0 IGO · updated irregular (2017, 2019 and 2022 editions)

Households of one person, from the same UN collection as the single-parent share and with the same limits: one to three readings per country, from sources that sort households differently, and few after 2019. It rises with age and with income, and falls with family size. That is three different things in one number. No "better" direction is set.

Price level

Price level of household consumption, compared with the US (Penn World Table)

Groningen Growth and Development Centre, University of Groningen · via DataverseNL · CC BY 4.0 · updated irregular (new versions every few years)

How expensive the things households buy are in a country, compared with the US in the same year, when money is changed at the market exchange rate. A value of 0.5 means a typical basket of goods and services costs about half what it would in the US. Richer countries tend to be more expensive. It comes from the same price comparisons used to adjust GDP for what money buys, so it shares a building block with GDP per capita (PPP). Years in which the Penn World Table flags the price comparison as unreliable are left out. No "better" direction is set.

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 18,622 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated V-Dem v16; V-Party v2. How the country data works · explore One-person households and Price level

This page shows that two measures go together. It does not show that One-person households changes Price level, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.