Can Stimulating Demand Drive Costs Down? World War II as a Natural Experiment
利用二战期间美国军事生产的大规模数据，研究发现外生技术进步和内生生产经验对单位成本下降的贡献大致相当，且需求外生性缓解了反向因果和多重共线性问题。
U.S. military production during World War II increased at an impressive rate and led to large declines in unit costs. However, the literature has focused on elucidating detailed mechanisms behind this relationship, using small datasets on specific products. Here we take a step back and, looking at an unprecedently large collection of data, we show that both exogenous technological progress and endogenous effects from increasing production experience were important, in roughly similar proportions. The demand for military products was largely exogenous, and the correlation between production, cumulative production, and time was weak, limiting issues of reverse causality and multicollinearity.