Objectives, Research Design, and Implementation of the Incap Longitudinal Study

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Abstract
The INCAP longitudinal study (1969–1977) was carried out in four Guatemalan villages to assess the effects of intra-uterine and preschool malnutrition on growth and mental development. To achieve this, food supplements were provided to pregnant women and young children. Two villages were given a high-protein, high-energy drink and two a no-protein, low-energy drink. Both supplements contained vitamins and minerals. The key features of the final study design implemented in 1969 are noted, together with its strengths and weaknesses. The selection of the study villages is described in detail, and the nature of the randomized nutritional intervention and that of the medical care programme offered to all the villages are presented. The methods of data collection and quality-control procedures are also detailed. The information should be of interest to those wishing to use and understand the INCAP/Cornell data set.