Fetal Iodine Deficiency and Schooling: A Replication of Field,Robles, and Torero (2009)*

Scholars have theorized that congenital health endowment is an important determinant of economic outcomes later in a person's life. Field, Robles, and Torero (2009, American Economic Journal: Applied Economics 1, 140–169) find large increases in educational attainment caused by a reduction of fetal iodine deficiency following a set of iodine supplementation programs in Tanzania. We revisit the Tanzanian iodine programs with a narrow and wide replication of the study by Field et al. We are able to exactly replicate the original results. We find, however, that the findings are sensitive to alternative specification choices and sample restrictions. We try to address some of these concerns in the wide replication; we increase the sample size fourfold, and we improve the precision of the treatment variable by incorporating new institutional and medical insights. Despite the improvements, no effect is found. We conclude that the available data do not provide sufficient power to detect a possible effect, as treatment assignment cannot be measured with sufficient precision.