Across 160 countries, Independent opposition and Price level rise and fall together at r = +0.51 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) leaves r = +0.42, which could easily be chance (q = 0.055, allowing for the many pairs tested, and allowing for countries in the same region being alike).
Comparing countries across the middle half of price level, 0.336 to 0.638 ratio to the US, independent opposition is better by 0.897 points at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 0.926 points.
Link before adjusting (r)+0.511p = 5.1e-12 · 160 countries
After adjusting for national income+0.422p = 3.1e-8 · likely range [+0.28, +0.54]
p, allowing for regions0.006standard error 0.102 · 7 regions
Check for luck (q)0.055across 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.
Independent opposition · score (higher = more independent)link with income +0.45 · moderate
Price level · ratio to the US (US = 1)link with income +0.72 · 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
+0.511
5.1e-12
160
By rank (Spearman), not adjusted
+0.564
7.7e-15
160
Standard (Pearson), adjusted for national income
+0.422
3.1e-8
160
By rank (Spearman), adjusted for national income
+0.377
9.6e-7
160
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 160 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: +0.089 (a minus sign means it grew).
How solid is it?
Leaving out one country at a time, r ranges from +0.407 (without BLR) to +0.432 (without ZWE). 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 (-0.015).
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
+0.19
Europe & Central Asia
48
+0.39
Latin America & Caribbean
23
+0.28
Middle East, North Africa, Afghanistan & Pakistan
18
+0.56
Sub-Saharan Africa
46
-0.00
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
54
+0.10
Middle third
53
+0.33
Richest third
53
+0.60
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
95
+0.38
Muslims
44
+0.05
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
France
25
+0.21
Never a European colony
19
+0.26
Spain
19
+0.22
United Kingdom
45
+0.35
By official ideology
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
Nationalist
24
+0.09
No strong official ideology
111
+0.40
By party system
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
A few parties banned
25
+0.48
No parties banned
117
+0.32
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 = +0.414 after dropping 10 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 34years. 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 = -0.027, 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 price level move with it.
Across countries (adjusted)+0.422for comparison
Within countries-0.055each country vs itself
…and vs the same year elsewhere-0.027q = 0.514 · 163 countries
Year-on-year changes+0.000q = 0.999
5,391 country-years (one country in one year), 163 countries, 1990–2023, about 33 years each on average. Share of the variation that happens within countries over time: 22% for Independent opposition, 14% 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): -0.027. 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
score (higher = more independent)
ratio to the US (US = 1)
Years
Chile CHL
3.13
0.63
2025, 2023
Ireland IRL
3.01
1.13
2025, 2023
Uruguay URY
2.96
0.777
2025, 2023
Netherlands NLD
2.86
0.888
2025, 2023
Belgium BEL
2.85
0.893
2025, 2023
Latvia LVA
2.84
0.672
2025, 2023
Slovak Republic SVK
2.84
0.703
2025, 2023
Denmark DNK
2.83
1.05
2025, 2023
New Zealand NZL
2.77
0.957
2025, 2023
Sweden SWE
2.77
0.874
2025, 2023
Korea, Rep. KOR
2.76
0.728
2025, 2023
Spain ESP
2.74
0.748
2025, 2023
Italy ITA
2.73
0.774
2025, 2023
Austria AUT
2.73
0.87
2025, 2023
Switzerland CHE
2.72
1.32
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. 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.
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.
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 2019–2025. 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 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 Independent opposition and Price level
This page shows that two measures go together. It does not show that Independent opposition changes Price level, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.
More links with Independent opposition or Price level