Ease of forming a party vs. Official ideology, strength
Holds up after adjusting for income
Across 169 countries, Ease of forming a party and Official ideology, strength rise and fall together at r = -0.62 (on a scale from −1 to +1, where 0 means no link). It holds up almost unchanged when only countries with similar income (GDP per person) are compared (r = -0.61, q = 0.019, allowing for the many pairs tested).
Comparing countries across the middle half of ease of forming a party, 0.334 to 2.12 points, official ideology, strength is 1 points lower at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 1.01 points.
Link before adjusting (r)-0.619p = 2.8e-19 · 169 countries
After adjusting for national income-0.614p = 8.4e-19 · likely range [-0.70, -0.51]
p, allowing for regions0.001standard error 0.102 · 7 regions
Check for luck (q)0.019across 17,292 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.
Ease of forming a party · score (higher = fewer barriers)link with income +0.38 · moderate
Official ideology, strength · score (higher = more)link with income -0.13 · independent
“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
-0.619
2.8e-19
169
By rank (Spearman), not adjusted
-0.543
2.3e-14
169
Standard (Pearson), adjusted for national income
-0.614
8.4e-19
169
By rank (Spearman), adjusted for national income
-0.539
4.7e-14
169
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 169 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: +0.005 (a minus sign means it grew).
How solid is it?
Leaving out one country at a time, r ranges from -0.623 (without KWT) to -0.596 (without SWZ). 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: SWZ (+0.019).
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
21
-0.74
Europe & Central Asia
49
-0.63
Latin America & Caribbean
23
-0.37
Middle East, North Africa, Afghanistan & Pakistan
22
-0.61
Sub-Saharan Africa
46
-0.54
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
57
-0.57
Middle third
56
-0.64
Richest third
56
-0.66
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
99
-0.57
Muslims
49
-0.44
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
-0.65
Never a European colony
21
-0.76
Spain
19
-0.27
United Kingdom
49
-0.48
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
25
-0.42
No strong official ideology
117
-0.19
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
26
-0.37
No parties banned
122
-0.33
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 = -0.556 after dropping 8 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.
The link also shows up within countries over time (r = -0.339). It holds even when looking only at changes from one year to the next (r = -0.158). This is the strongest kind of evidence available here: it holds when each country is compared only with itself, and it is not just a product of shared trends.
Across countries (adjusted)-0.614for comparison
Within countries-0.347each country vs itself
…and vs the same year elsewhere-0.339q = 0.000 · 176 countries
Year-on-year changes-0.158q = 0.000
5,934 country-years (one country in one year), 176 countries, 1990–2023, about 34 years each on average. Share of the variation that happens within countries over time: 15% for Ease of forming a party, 13% for Official ideology, strength. 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): -0.339. 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 = fewer barriers)
score (higher = more)
Years
United States USA
2.95
-0.008
2025, 2023
Costa Rica CRI
2.81
-0.994
2025, 2023
Sweden SWE
2.76
-1.59
2025, 2023
Argentina ARG
2.75
0.002
2025, 2023
Belgium BEL
2.72
-2.63
2025, 2023
Austria AUT
2.68
-2.54
2025, 2023
Italy ITA
2.66
-0.615
2025, 2023
United Kingdom GBR
2.65
-1.12
2025, 2023
Switzerland CHE
2.63
-2.9
2025, 2023
South Africa ZAF
2.6
0.042
2025, 2023
Trinidad and Tobago TTO
2.57
-1.42
2025, 2023
Denmark DNK
2.53
-1.97
2025, 2023
Cyprus CYP
2.51
-0.244
2025, 2023
Sri Lanka LKA
2.5
-1.89
2025, 2023
Japan JPN
2.48
-0.297
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. 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.
Barriers to forming a party (higher = fewer barriers)
V-Dem Institute, University of Gothenburg · CC BY-SA 4.0 · updated annual (V-Dem); V-Party per election, to 2019
How hard is it to start a new party? Experts answer from 0 ("parties are not allowed") to 4 ("no substantial barriers"), counting both legal hurdles such as deposits and membership rules and harassment of party leaders. V-Dem turns the answers into a score of about -4 to +4. A part of V-Dem's freedom of association index.
How far the government justifies itself with an official ideology
V-Dem Institute, University of Gothenburg · CC BY-SA 4.0 · updated annual (V-Dem); V-Party per election, to 2019
To what extent does the government promote a set of official beliefs, such as socialism, nationalism or a religion, to justify its rule? Experts answer from 0 ("not at all") to 4 ("almost exclusively"), and V-Dem turns the answers into a score of about -4 to +4. Which ideology it is appears in the "official ideology" label. V-Dem's coding of this question runs to 2023.
How this was computed
Data used: most recent value in 2010-2025; values come from 2020–2025. 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 17,292 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated V-Dem v16; V-Party v2. How the country data works · explore Ease of forming a party and Official ideology, strength
This page shows that two measures go together. It does not show that Ease of forming a party changes Official ideology, strength, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.
More links with Ease of forming a party or Official ideology, strength