What Is the Gini Coefficient
The Gini coefficient measures income or wealth inequality on a scale from 0 to 1. A value of 0 represents perfect equality (everyone earns the same), while 1 represents perfect inequality (one person holds all income). Published by the World Bank for most countries, it has become the standard metric for international inequality comparisons despite its inherent simplifications.
As of 2023, the most equal countries include Slovakia (0.232) and Slovenia (0.243), while the most unequal are South Africa (0.630) and Namibia (0.591). Japan sits at 0.334, slightly above the OECD average of 0.318. These numbers condense enormously complex distributional realities into single values, which is both their power and their limitation.
Calculation via the Lorenz Curve
The Gini coefficient is formally defined as twice the area between the Lorenz curve and the line of perfect equality. The Lorenz curve plots the cumulative share of income (vertical axis) against the cumulative share of population (horizontal axis). Under perfect equality, this curve is a 45-degree line; greater inequality causes it to bow downward, increasing the enclosed area.
MyRank's income percentile and the Gini coefficient serve complementary roles. The percentile tells you "where you stand," while the Gini coefficient describes "the shape of the distribution." At the same 50th percentile, a country with a high Gini coefficient will show a larger gap between the median and the mean, indicating that those above you are disproportionately far ahead.
Limitations and Misuse of the Gini Coefficient
Because the Gini coefficient compresses an entire distribution into a single number, information about distributional shape is lost. A society where the top 1% is extremely wealthy and a society with a hollowed-out middle class can produce identical Gini values despite having fundamentally different inequality structures. The same number can describe very different social realities.
Furthermore, the Gini coefficient typically measures only income inequality, not wealth inequality. In countries like Japan, where income inequality is moderate but asset inequality (particularly real estate) is substantial, the Gini coefficient alone fails to capture the full picture. Whether the calculation uses pre-tax or post-tax income also significantly affects the result - Nordic countries have relatively high pre-tax Gini values that drop dramatically after redistribution.
What the Gini Coefficient Means for Rankings
When viewing income rankings on MyRank, awareness of your country's Gini coefficient deepens interpretation. In high-Gini countries, the absolute income gap between you and those above you is larger at any given percentile. A 10-percentile improvement in a high-inequality country represents a much larger income jump than the same improvement in a low-inequality country.
Conversely, in low-Gini countries, even substantial percentile shifts correspond to relatively modest differences in actual living standards. Understanding the distributional shape behind the numbers - not just your position within it - is the first step toward genuine data literacy. Rankings without distributional context tell only half the story.