Literally, inequality refers to a lack of evenness or the presence of social disparity—an imbalance in the distribution of opportunities, services, and benefits. It implies that different individuals or groups have unequal or varying degrees of access to these essential elements of development.
Inequality is fundamentally about relative access: how different population segments compare in their ability to obtain development opportunities and outcomes. As inequality grows, disparity also increases proportionally, further widening the gap between social groups.
Inequality arises due to several overlapping factors:
Physical attributes: Natural abilities and talents are not distributed equally among individuals.
Personal preferences: People make different choices between leisure and work, affecting economic outcomes.
Social processes: Cultural and societal pressures influence whether people work, and how much they work, varying by group.
Public policies: Government actions impact the distribution of resources and services, sometimes unintentionally increasing inequality.
The analysis of inequality is critical for public policy formulation. It enables decision-makers to identify target groups or regions that are systematically disadvantaged, ensuring more effective and inclusive policy design.
The range is calculated as the difference between the highest and lowest observations. For example, given the values 115, 78, 45, and 220, the range is (220–45) = 175.
This method is simple and gives a quick impression of inequality, but it only considers two observations and ignores the rest. It is also highly sensitive to outliers.
The range ratio is computed by dividing the income or expenditure of selected highest and lowest percentiles.
Example: If incomes of 15 persons are 45, 48, 78, 87, 98, 120, 200, 221, 238, 250, 252, 267, 287, 322, and 327, then:
95th percentile (14th person) = 322; 5th percentile (1st person) = 45. Range ratio = 322/45 = 7.16
This method is easy to compute and reduces outlier influence slightly, but like range, it still considers only two values and omits the rest.
The McLoone Index is the sum of all values below the median divided by the product of the median and the number of such observations.
In the above data, the median = 221, and values below it are: 45, 48, 78, 87, 98, 120, 200. Their sum = 676.
McLoone Index = 676 / (221 × 7) = 0.44
This method provides useful insight into the lower half of the distribution, but ignores values above the median.
The coefficient of variation is the standard deviation divided by the mean, and it reflects the degree of income dispersion.
Given the following data:
| Person | Country 1 | Country 2 | Country 3 |
|---|---|---|---|
| 1 | 50 | 48 | |
| 2 | 50 | 18 | 50 |
| 3 | 50 | 78 | 51 |
| 4 | 50 | 12 | 49 |
| 5 | 50 | 52 | 48 |
| Mean | 50 | 50 | 50 |
| SD | 0.0 | 1.4 | 32.2 |
| CV | 0.00 | 0.03 | 0.64 |
Country 1 shows perfect equality, Country 2 shows slight variation, and Country 3 has extreme income skewness.
The Lorenz Curve is a graphical representation of income distribution. The population (households) is plotted on the x-axis (0% to 100%) and income on the y-axis (0% to 100%).
If income were equally distributed, the Lorenz curve would follow the 45-degree line of perfect equality. Deviations from this line indicate inequality.
The Gini coefficient is derived from the Lorenz Curve as A / (A + B), where A is the area between the line of perfect equality and the Lorenz curve, and B is the area under the Lorenz curve.
Limitation: When Lorenz curves intersect, it's unclear which distribution has greater inequality. It also ignores lifetime income and differences due to age groups (young, working, retired).
The quality of life involves both income and non-income factors. Non-income dimensions include access to safe drinking water, sanitation, education, healthcare, and employment.
Inequality in these areas varies across social groups, genders, and regions, and is evaluated using inequality indicators.