Growth, mobility and social progress

We evaluate social progress on the basis of panel data on individual incomes by comparing the value of social welfare in the observed panel data to its value in a situation where individuals receive their first period income in each period. We derive necessary conditions for the welfare gain to be positive, and show how it can be decomposed in an effect of economic growth, a mobility effect and a cost due to aversion to time fluctuations given individuals’ ranks in the income distribution. The mobility effect, generated by reranking in the income distribution has two components: a cost due to time fluctuations in incomes and a benefit, due to equalization in time averaged incomes. We illustrate the analysis using CNEF data for Australia, Korea, Germany, Russia, Switzerland and the US. Our results indicate that the largest component of social progress is the equalization of time averaged income, induced by reranking. In countries with high growth (Australia, Korea and Russia), the growth effect is larger than the mobility effect, but in countries with low growth (Germany, Switzerland and the US), the opposite holds true. The poor performance of the US is explained by the large costs of income fluctuations and the way economic growth is distributed.