Interpretation of Men’s Labor Market Results

C. Interpretation of Men’s Labor Market Results

As an external check to the validity, I compare the results to those found in the devel- opment and medical literatures, which report average treatment effects on the treated for patients preidentifi ed as anemic or iron defi cient. My results pertain to an ag- gregate level effect on the total population, not solely anemic patients. 30 I convert the average aggregate result to a parameter similar to an “average treatment effect on the treated” or “an intent to treat effect“ for an iron defi cient individual. The fortifi cation program differentially affected individuals, with larger benefi ts accruing to those with lower initial levels of iron. I assume that only those individuals consuming less than 75 percent of their RDA experienced gains in health from the program and thus gains in income. Concentrating the full reduced- form impact of the program onto this portion of the population gives the average income gain to the iron- defi cient individual. Using the results from Column 2 of Table 5, a difference of one mg in preintervention iron consumption implies a differential 1.05 percent gain in income. On average, the program increased iron consumption by 2 mg per day Gerrior, Bente, and Hiza 2004. Therefore, the full reduced- form effect on income of the program was 2.1 percent. Dividing by the proportion of the sample that con- sumed less than 75 percent of the RDA suggests that the program increased incomes by 5.25 percent at the individual level. Applying this procedure to labor supply sug- gests that the program increased weeks worked by 1.82 percent at the individual level. The remainder, 3.43 percent, can be interpreted as the productivity effect wage hour. A major contribution of this paper is the result that increased labor supply makes up a large portion of the total increase in income associated with the iron fortifi cation program. Estimated benefi t- cost ratios that rely solely on the productivity impacts will underestimate the true benefi ts of an iron fortifi cation campaign. The result for the individual productivity effect is well within the range of values found in fi eld experiments in the developing country context. Thomas et al. 2006 fi nd a 30 percent increase in productivity for preidentifi ed anemic self- employed In- donesian males in a randomized study of iron supplementation. Rubber tappers in Indonesia were found to have increased productivity by 10–15 percent Basta et al. 1979. Chinese textile workers increased production effi ciency by 5 percent after supplementation Li et al. 1994, and Sri Lankan tea pickers increased the amount of tea picked by 1.2 percent Edgerton et al. 1979.

VI. Iron Fortifi cation’s Contemporaneous Effects on School Enrollment