Ability Grouping and Academic Inequality: Evidence from Trinidad and Tobago

Clement (Kirabo) Jackson, Cornell University ILR School

Abstract

In Trinidad and Tobago students are assigned to secondary schools after fifth grade based on achievement tests, generating large differences in school and peer quality. Using instrumental variables to address self-selection bias, I find that being assigned to a school with high-achieving peers has large positive effects on examination performance, particularly for girls. This suggests that ability grouping (or school tracking) reinforces achievement differences by assigning the weakest students to schools that provide the least value-added. While students benefit from attending schools with brighter peers on average, the marginal effect is non-linear such that there are small benefits to attending high-achievement schools over average schools, while there are sizable benefits to attending average schools over low-achievement schools. This suggests that much of the costs of school ability grouping are borne by those consigned to low-achievement schools at the lower end of the achievement distribution.