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.
Lafond, F., Greenwald, D. & Farmer, J.D. (2022). 'Can Stimulating Demand Drive Costs Down? World War II as a Natural Experiment'. The Journal of Economic History, Vol 82, Issue 3, pp.727-764