Income Distribution

Income distribution concerns how resources are shared across households and individuals, rather than simply how much an economy produces. But the name of a topic does not settle the statistical measure used to study it. The World Bank's Gini indicator can describe either income or consumption expenditure, depending on the underlying survey. These concepts must remain explicit when comparing countries or years. s3

The Gini index summarizes inequality on a scale from zero, representing perfect equality, to 100, representing perfect inequality. It is based on the distance between the observed distribution and a hypothetical equal distribution. It does not identify which particular households gained or lost resources, and a single national value cannot describe every difference within a country. s3

The Statistical Center of Iran conducts the Household Expenditure and Income Survey, known as HEIS. Despite collecting income information, the survey has a strong expenditure focus. The World Bank describes it as nationally representative, with sampling stratified across urban and rural areas within provinces. Its international poverty and inequality welfare aggregate uses household expenditure per person, adjusted for differences in prices over time and across places. s2

This makes the resulting Gini an expenditure-inequality measure. It should not be relabeled as wage inequality, a wealth-concentration measure, or a direct estimate of the share of income received by the richest households. Survey responses are self-reported. Recall periods also differ across items: many expenditures use the previous month, while some less frequent expenditures and income components use the previous year. Estimated values are included for some items that were not purchased. These details matter when interpreting what household resources mean in the published statistics. s2

The World Bank series reproduced by the Federal Reserve Bank of St. Louis shows an increase from 34.4 in 2012 to 37.4 in 2018, followed by a decline to 34.8 in 2022. The value then rose to 35.9 in 2023. This is an uneven sequence, rather than evidence of a continuous improvement or deterioration. The accompanying dataset preserves the published one-decimal precision. s1

These movements describe relative dispersion. They do not establish whether purchasing power increased, whether poverty declined, or which policies caused the changes. Those questions require additional evidence on real household expenditure, prices, and the distribution of gains. Keeping inequality separate from poverty avoids treating a lower Gini as automatic proof that households became better off. The Gini summarizes relative distribution; poverty statistics assess resources against a specified threshold. s2s3

Iran, national · gregorian