Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Summan, Nandi, and Bloom (2023), hereafter SNB, find that exposure during infancy to India’s Universal Immunization Programme (UIP) increased wages and per-capita household expenditure in early adulthood. SNB come to this conclusion by regressing these outcomes on a treatment indicator that depends upon year and district of birth while controlling for age at follow-up. Because year of birth and age are nearly collinear, SNB’s identifying variation comes from the progression of time during the follow-up period, rather than variation in access to the program. Within the 12-month follow-up period, those interviewed later were more likely to have been treated and, on average, reported higher wages and household expenditure. Wages and household expenditure, however, rose by at least as much in a control group composed of people too old to have been exposed as infants to the UIP. SNB’s results are best explained by inflation, economic growth, and nonrandom survey sequencing during the follow-up survey period.