Trends in Measures of Economic Inequality in Japan

抄録

The Gini coefficient and the relative poverty rate are among the most widely employed metrics for assessing economic inequality. In Japan, these indicators are derived from the Comprehensive Survey of Living Conditions (CSLC), the Survey on the Redistribution of Income (SRI), and the National Survey of Family Income, Consumption and Wealth (NSFICW; formerly the National Survey of Family Income and Expenditure), with aggregated results publicly released. It is well documented, however, that the reported values vary systematically depending on the source. This study examines the Gini coefficient and the relative poverty rate, undertaking a cross-source comparison. Our analysis shows that, over the 2010s, income inequality measured on a market-income basis increased, while redistribution consistently attenuated this rise across all datasets. Estimates from the CSLC and SRI are persistently higher than those from the NSFICW, a pattern that remains stable over time. Discrepancies between the CSLC/SRI and the NSFICW are particularly pronounced among younger and older age groups, as well as single-person households. These results highlight the importance of employing multiple statistical sources in the measurement of income inequality.