哪裡是「機會之地」呢？看看美國研究。
1. 爸媽的收入每增加 10 百分位，孩子日後就增加 3.4 百分位。
2. 爸媽在收入底層，孩子翻到收入頂層的比例，在好城市的機會最大。
3. 想讓孩子翻身，在這樣的地方養小孩最有機會：比較少的居民隔離、比較少的收入不平等、比較好的小學、比較好的社會資本、比較好的家庭穩定性。
First, we characterize the joint distribution of parent and child income at the national level. The conditional expectation of child income given parent income is linear in percentile ranks. On average, a 10 percentile increase in parent income is associated with a 3.4 percentile increase in a child’s income. Second, intergenerational mobility varies substantially across areas within the United States. For example, the probability that a child reaches the top quintile of the national income distribution starting from a family in the bottom quintile is 4.4% in Charlotte but 12.9% in San Jose. Third, we explore the factors correlated with upward mobility. High mobility areas have (i) less residential segregation, (ii) less income inequality, (iii) better primary schools, (iv) greater social capital, and (v) greater family stability.
