The 1918 U.S. Influenza Pandemic as a Natural Experiment, Revisited
Ryan P. Brown, Duke University
Douglas Almond's use of the 1918 U.S. influenza pandemic as a natural experiment led to the seminal works on the subject of in utero health's impact on later life outcomes. The identification strength of his work, though, is driven by the inherent natural experiment supposition of random assignment. By using data from the 1920 and 1930 U.S. Censuses, this study investigates this keystone assumption and shows that the families of the "treatment" cohort were significantly less literate and economically prosperous than the families of the "control" group. Additionally, when proxies for childhood environment are added to Almond’s analyses, his findings are appreciably reduced in magnitude and significance. This research implies that failing to control for the first order effect of parent's education and wealth on a child's long-run outcomes, eliminates Almond's ability to use the 1918 U.S. influenza pandemic to make direct inferences regarding fetal health's impact on long-term wellbeing.