Women, War, and Weak Instruments: A Re-Reassessment of the Role of World War II on Women’s Labor Supply

Michael Briskin, Boston University

This paper revisits World War II’s effect on female labor force participation (FLFP) using newly available complete count census data from 1940 and 1950. Compared to seminal papers in the literature—such as Acemoglu, Autor, and Lyle (2004) and Goldin and Olivetti (2013)—which rely on 1% census samples and use the state-level military mobilization rate of men as a source of variation in women’s labor supply, I find substantially smaller effects of the war on FLFP in the complete count data. The mobilization rate is therefore a weak instrument for growth in FLFP, calling into question estimates that use mobilization to instrument for FLFP’s effects on wages. To understand why earlier studies using 1% samples reached different conclusions, I repeat these analyses using 10,000 random 1% subsamples of the complete count data, comparable to those used in earlier work. In all cases, the distribution of estimates varies widely, suggesting that different census samples can generate very different conclusions when estimating the effects of state-level treatment. These findings challenge previous conclusions about WWII’s impact on women’s labor force participation and highlight broader methodological concerns for research using small census samples.

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 Presented in Session 75. Women at Work