Immigration, Skill Mix, and Capital Skill Complementarity
研究美国制造业工厂在1980-1990年代因移民涌入导致低技能劳动力供给增加，进而减少自动化机械投资，揭示了资本与不同技能劳动力的替代与互补关系。
Over the past thirty years, U.S. manufacturing plants invested heavily in automation machinery. This paper shows these investments substituted for the least-skilled workers and complemented middle-skilled workers at equipment and fabricated metal plants. Specifically, it exploits the fact that some metropolitan areas experienced faster growth in the relative supply of less-skilled labor in the 1980s and 1990s due to an immigration wave and the tendency of immigrants to regionally cluster. Plants in these areas adopted significantly less machinery per unit output, despite having similar adoption plans initially. The results imply that fixed rental rates for automation machinery reduce the effect that immigration has on less-skilled relative wages. Copyright 2011, Oxford University Press.