Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This study offers a simultaneous equations model of the birth process with seven endogenous variables: four birth inputs (maternal smoking, maternal drinking, first trimester prenatal care, and maternal weight gain) and three birth outputs (gestational age, birth length, and birth weight). The data are taken from the National Longitudinal Survey of Youth. Our analysis conditions on twenty-nine exogenous variables including four racial dummies to account for the widely cited racial differences in birth outputs. We find that there is sizeable correlation between the disturbances in the four input and three output equations and among output disturbances, and that results from our simultaneous equations model are substantially different from those using the single-equation approach. It appears that the High/Low Risk Birth Weight Puzzle remains unresolved under our modeling framework. Copyright Springer-Verlag 2003