the result that estimates that do not control for all of these capital stocks and for the family background characteristics in the early-adolescent stage (that also are likely to be correlated because of the role of family background in determining the human capital investments)—as in most of the literature that only includes schooling—are likely to be subject to omitted variable bias because of the failure to control for the other components of human capital and for parental background characteristics. We investigate how important this problem is by comparing alternative specifications that have multiple measures of different components of human capital plus family background with one in only schooling is included. <u>Third, most of the focus in the literature is</u> related to a few components of Y, primarily age of first union and age of first parenting. We investigate these outcomes, but also consider a number of other outcomes noted above and elaborated on in Section 4.2 -- whether age gap between first union and first parenting, whether young first union (under 18 y of age), whether young first parenting (under 18 y of age), partner characteristics (age gap, schooling attainment, health) and partner’s parental family characteristics (parental schooling attainment, land holding). This permits a much richer assessment of the impact of schooling on the initial union formation and parenting.

# **Section 4. Data**

The data demands are considerable for estimating the relations posited in Section 3. We utilize an unusually rich longitudinal data set collected over a 35-year period with union and parenting histories and alternative measures of human capital (e.g., school attainment, height to represent long-run nutritional and health status), family background and shocks from an experimental intervention and market and policy changes. We first provide a brief general description of the data<sup>6</sup> and then focus on the particular variables that we use in the analysis.

## **Section 4.1 General Description of the Data**

In the early and mid-1960s, protein deficiency was seen as the single most important nutritional problem facing the poor in developing countries and there was considerable interest in the possibility that this deficiency affected children’s ability to learn. The Institute of Nutrition for Central America and Panama (INCAP), based in Guatemala, became the locus of a series of preliminary studies on this subject in the latter half of the 1960s (see Habicht and Martorell 1992, Martorell, Habicht and Rivera 1995 and, especially, Read and Habicht 1992). These informed the development of a larger scale supplementation trial that began in 1969.

The data used in this study are from that larger supplementation trial, collected for individuals who were 0-7 y old during 1969-77 in four villages in Eastern Guatemala. Three villages—San Juan, Conacaste and Santo Domingo—are located in mountainous areas with shallow soils, while the agricultural potential of Espíritu Santo, located in a river valley, is somewhat higher. All four villages are located relatively close to the Atlantic Highway, connecting Guatemala City to Guatemala’s Caribbean coast—from 36km to 102km from Guatemala City. From January 1969 to February 1977 INCAP implemented a nutritional supplementation trial in these four villages, together with data collection on child growth and development.<sup>7</sup> The data collection focused on all

> 6 For more extensive discussion of the data, see Grajeda _et al._ (2005), Hoddinott, Behrman and Martorell (2005), Maluccio _et al._ (2005b), Martorell _et al._ (2005), Quisumbing _et al._ (2005), Ramakrishna _et al._ (2005) and Stein _et al._ (2005).

> 7 The intervention began in the larger villages, Santo Domingo and Conacaste, in February 1969, and in the smaller villages, Espíritu Santo and San Juan, in May 1969.

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