Put another way, what matters for life satisfaction is the growth not of mean income but of median income – the income of the typical person. Consider a population of ten people (say, a factory) in which the managing director earns $150,000 a year and the other nine, all workers, earn $10,000 each.
换句话说，决定生活满意度的不是平均收入的增长，而是中位收入（即最典型人口的收入）的增长。考虑一个十人社会（比如一家工厂），董事每年赚15万美元，其他九名工人每人赚1万美元。他们的平均收入是2.5万美元，但90%的人只能赚1万美元。在这样的收入分配下，增长会提高典型人口的幸福感才怪。