lower levels than the total population. Reductions in BMI are also of a lower magnitude than those in the general population, but still significant.

Table 9 shows the estimation based on the original evaluation design. That is, estimating the effect of the intervention comparing individuals from households in original treatment and control villages, limited to the set of households that were classified as poor in 1997. This comparison measures an exposure differential of approximately 18 months; the average time between when the intervention began, until when control villages received the program at the end of 1999.

Even with this differential exposure of only 18 months, the short and mid-term evaluations identified positive effects of PROSPERA on the height indicator in children under 5 years of age. It is especially relevant to analyze the possible long-term effect of the program on height using the original evaluation design for groups with exposure during the critical periods for the development, in order to identify whether these effects persist in the long term.

In addition, for the set of the three groups with exposure in critical periods for growth, we identified an effect on height of 2.93 cm. This is consistent with, and of similar magnitude to, the estimated effect using as the comparison group the population that was 15 years of age or older in 1997, who did not receive the intervention during their critical periods for development.

Table 8. Contribution of PROSPERA to height and schooling, and to other relevant variables by time of exposure of populations that speak an indigenous language.

||(1)|(2)|(4)|(7)|(8)|
|---|---|---|---|---|---|
|VARIABLES|Mobility<br>height|Mobility<br>education|BMI|Cognitive<br>score|Memory<br>score|
|Group 1 vs Group 0|2.327***|4.593***|-5.300***|0.766**|0.987***|
||(0.742)|(0.377)|(0.866)|(0.337)|(0.148)|
|Observations|169|312|303|299|314|
|Group 2 vs Group 0|2.834***|4.542***|-4.382***|0.528*|0.865***|
||(0.994)|(0.692)|(0.797)|(0.295)|(0.152)|
|Observations|292|607|591|587|609|
|Group 3 vs Group 0|1.233|2.440***|-1.662***|0.558**|0.587***|
||(0.923)|(0.377)|(0.568)|(0.267)|(0.168)|
|Observations|197|401|394|380|403|
|Group 1,2 and 3|3.324***|4.298***|-4.601***|0.683**|0.930***|
|vs Group 0|(0.519)|(0.443)|(1.103)|(0.278)|(0.168)|
|Observations|510|1,045|1,020|1,007|1,047|

Notes: The estimations are contrasts between the matching differences of the indicator between the group of exposure and the comparison group. Variables for matching: ln of the provider’s height, eligibility score of PROSPERA in 1997 (linear and square), classification as poor household in 1997, gender, provider’s gender, provider’s age (linear and square), provider’s education, in 1997, two-months period when the transfers of PROSPERA were first received in the household of origin, number of persons in the household in 1997, and labor income of the household in 1997. Standard errors in parentheses. Level of significance *** _p<_ 0.01, ** _p<_ 0.05, * _p<_ 0.1. Source: estimations by propensity score matching based on data from the Evaluation of Rural Households Survey (ENCEL) 2017, complemented with data from the panel of ENCEL 1997-2000.

We find that the estimated positive effect of PROSPERA is driven by the groups in treatment villages who received the intervention in critical periods for building human capital. No effects were found in the group that had passed the critical periods of growth (Group 0, youth over 15 years of age in 1997).

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