retardation among children (Martorell and Ho 1984). In Rounds 1 and 3, 10 and 3 percent of children had diarrhea two weeks prior to the survey.

_Hemoglobin count and anemia._ The study measured the hemoglobin levels from blood samples taken from children six months of age or older.<sup>12</sup> A hemoglobin level below the cut-off of 11.0 grams per 100 milliliters for children age six to 59 months of age is considered to be indicative of iron deficiency related anemia (World Health Organization 2001). Iron deficiency is shown to have deleterious consequences for children’s cognitive and motor functioning and may impair their ability to resist and successfully recover from infections (e.g., Grantham-McGregor and Ani 2001, Oppenheimer 2001; Pollitt 1997). Forty-six percent of our sample children had readings below 11 grams per 100 milliliters in Round 1, with the mean level of hemoglobin for children of 11.4 in the latest round.

# **3. Methodology**

We want to estimate the impact of the program (P) on a number of outcomes (Y) such as the quantitative goals of the ECD project. The estimates that we present, both the preferred difference-in-difference propensity score matching estimates and the differencein-difference estimates, are “intent to treat” effects (that is, the impact of having the ECD program, on average, for all children in a given age range in the barangay, whether or not all of the children in the barangay actually received treatment). Estimating the impact of the program on the children who actually were treated (that is, the “treatment-on-thetreated”) is conceptually complex and difficult to implement because: (1) the program has several components, some new (such as child minding and the Child Development Workers) and some being improvements on already existing services such as growth monitoring and micronutrient supplementation; (2) the delivery of many of the program components is not centralized, so actual treatment under various components is difficult to ascertain and model; and (3) information campaigns about ECD in the community as well as home-based visits are an important aspect of the program mechanisms. In all, program impact is not likely to depend on service utilization in ways that may be true for programs that offer a single centralized service.<sup>13</sup> ________________ 12 Children less than age six months are generally not included because among full-term infants the risk of iron deficiency in this age range is relatively low due to adequate iron provisions from the perinatal period (World Health Organization 2001). Hemoglobin levels were determined by diluting blood samples with a cyanmethemoglobin reagent in a spectrophotometer and using the proportional relationship of the absorbance of the reagent with the concentration of hemoglobin to determine the latter quantity. This method is one of two generally recommended as best for assessing hemoglobin levels in surveys (World Health Organization, 2001).

13 Moreover, for some of the new components of the program such as child minding, utilization rates were far too low to allow us to use them in the analysis. Several other program components such as receiving home visits from barangay health workers, immunization, or being weighed at the barangay health center are difficult to examine because so few children did not receive these services. Thus the impact of the utilization of each ECD treatment is likely to provide a biased estimate of the overall ECD program effect. Nevertheless, we did experiment with defining treatment as whether the child had any contact with the barangay health station in the year prior to the survey for children living in program regions 6 and 7 only. We 13