Previous studies often interpret the positive impact of high-skill human capital on the mean wages of low-skill workers as evidence of human capital externalities. Using a grouped IV quantile technique, we uncover a distributional wage effect of high-skill human capital that is difficult to reconcile with the standard models of human capital externalities: the city-level share of college graduates has a positive impact on the wages of low-skill workers at the lower, but not the upper, quantiles of the wage distribution. We then provide a comprehensive assessment and discussion of the effect of high-skill human capital on low-skill wages in different occupations. We find a large and positive wage effect in the service occupations but not in the manufacturing occupations. We argue that consumption spillover, instead of human capital externality, is the underlying mechanism. These findings invite reinterpretation of previous studies on human capital externalities in low-skill labor markets.

先前的研究通常将高技能人力资本对低技能工人的平均工资的积极影响解释为人力资本外部性的证据。使用分组IV分位数技术，我们发现了高技能人力资本的分配工资效应，该效应很难与人力资本外部性的标准模型相吻合：城市级大学毕业生的比例对低收入者的工资具有积极影响-技术工人在工资分配的较低（而不是较高）分位数。然后，我们对高技能人力资本对不同职业中低技能工资的影响进行了全面的评估和讨论。我们发现服务业产生了巨大的积极工资效应，而制造业则没有。我们认为，消费溢出而不是人力资本外部性，是潜在的机制。这些发现要求重新解释以前关于低技能劳动力市场中人力资本外部性的研究。