Abstract
This paper documents the stability, predictive power, and sensitivity of mental and motor development scales and pre-school cognitive tests in the context of economically impoverished populations in low-income countries. Stability and predictive power comprise forecasting; stability includes repeated measures using the same test, whereas predictive power includes different tests. Sensitivity is the track record of the test in discriminating among groups of children exposed to different nutritional interventions. Psychometric data from three longitudinal studies of the assessment of the impact of early supplementary feeding on child development were used. Two studies were conducted in West Java, Indonesia, and the third study was carried out in El Oriente, Guatemala. Repeated measures allowed for the calculation of stability and predictive correlation coefficients. the mental development scales administered up to about 18 months had modest stability but no predictive power. This trend changed during the second year of life as the strength of the stability and predictive power increased. the pre-school tests were good predictors of a child's enrollment and school achievement. the findings on infant scales and pre-school tests agree with what has been reported in other populations in industrialized countries. There is no reason to believe that the developmental risk of the subjects that were assessed in each of the three target studies strengthens the psychometric attributes that were evaluated.