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.

二战期间美国的军事生产以惊人的速度增长，导致单位成本大幅下降。然而，文献集中在阐明这种关系背后的详细机制，使用特定产品的小型数据集。在这里，我们退后一步，查看前所未有的大量数据，我们表明外生技术进步和增加生产经验的内生效应都很重要，比例大致相似。军品需求在很大程度上是外生的，产量、累计产量和时间之间的相关性较弱，限制了反向因果关系和多重共线性问题。