Labor Market Returns to an Early Childhood Stimulation Intervention in Jamaica

In 1986-1987, the Jamaican Study enrolled 129 growth stunted and disadvantaged children aged 9-24 months that lived in Kingston, Jamaica. Half of the children were randomized into a cognitive stimulation intervention which lasted 18 months (S. P.Walker, S. M. Chang, C. A. Powell, S. M. Grantham-McGregor, The Lancet 366, 1804 (2005)). A matched non-stunted group was also followed for comparison purposes. We resurveyed both the stunted and non-stunted samples in 2007-08, some 20 years after the original intervention, when the participants were approximately 22 years old. We found and interviewed 105 out of the original 129 stunted study participants. We estimated the impact of the stimulation intervention on earnings by comparing the earnings of the stunted-treatment group to those of the stunted-comparison group.