Relationship between hemoglobin and cognition among children in rural China

• We estimate multivariate cubic spline functions of the haemoglobin-cognitive and haemoglobin-non cognitive relationship for different sub-populations and age groups of Chinese children. In all cubic spline estimations we control standard for gender, age, household wealth and parental education. • We pool the baseline survey data from 8 randomized control trials conducted by REAP. This results in an extra-ordinary large sample consisting of 4,000 infants between 6 months and 5 years, 23,000 children between age 5 and 11 and 22,000 children between age 12 and 14 years old. Data has been collected across several Chinese provinces: Shaanxi, Ningxia, Qinghai, Gansu, Hebei, and Guizhou • Overall we find the relationship between haemoglobin concentation and measures of human capital to be concave. • For mathematics we find that moving from a concentration of 110 to 130 Hb g/dL is, on average and controlling for socio-economic factors, associated with 0.2 of a standard deviation improvement in test scores. • Using the Bayley Scales to estimate adjusted cubic splines for infants from 6 to 30 months we find considerable slope differences between the two sub-scales of the Bayley test. The association between Hb concentration and the Psychomotor Development Index (PDI) is stronger than the association of Hb concentration and the Mental Developmental Index (MDI). This should not be surprising given that the psychomotor scores are found to be better predictors of later cognitive performance (Pollitt and Gorman, 1990).