Wilkinson and Pickett compiled an index of health and social problems for the wealthiest countries in the world. They included:
Life expectancy and infant mortality
Level of trust
Children’s educational performance
When they graphed the Index of Health and Social Problems against income inequality, the found that more unequal countries did worse on every criterion. For the overall index, this was a strong relationship with most points close to a straight line.
This means that if a country has very unequal distribution of income, you can be sure that it also has severe problems with health, crime, education, and, yes, social mobility.
The countries with the best quality of life are Japan, Sweden, Norway, the Netherlands, Switzerland and Finland. Dead last in their sample of 21 wealthy democratic countries was the U.S., followed by Portugal and the U.K.
Social problems of all kinds follow from inequality. One simple measure of inequality is the ratio of income of the top 20% compared to the bottom 20% of the population. In Japan and Scandinavia, a typical ratio is that the richest fifth are four times better off than the poorest quintile. For Portugal and the U.S, the ratio is around 8. meaning that inequality is twice as great.