Learning by Working in Big Cities
研究发现大城市的高收入并非源于高能力工人的聚集，而是来自即时静态溢价和更宝贵的工作经验积累，且这种经验价值在离开大城市后仍持续存在。
Individual earnings are higher in bigger cities.We consider three reasons: spatial sorting of initially more productive workers, static advantages from workers' current location, and learning by working in bigger cities. Using rich administrative data for Spain, we find that workers in bigger cities do not have higher initial unobserved ability as reflected in fixed effects. Instead, they obtain an immediate static premium and accumulate more valuable experience. The additional value of experience in bigger cities persists after leaving and is stronger for those with higher initial ability. This explains both the higher mean and greater dispersion of earnings in bigger cities.