It is known that policymakers are targeting cognitive achievement and not time in school (Glewwe, 2002). Therefore, to measure the adverse consequences of child labour on a child’s human capital development, some measure of cognitive attainment (test scores) must be used.
Furthermore, Grade-for-Age is a measure of schooling attainment used when the target sample is younger and still in school. This also allows for variation in measures of schooling success even within samples based on the same grade as the most successful students are those who attained the given grade at the youngest age. This outcome measure is interpreted as multi-year process rather than a single year process because the current grade attainment reflects past as well as current child labour and schooling decisions.
The possession of reading, language and mathematical skills that the test scores measure, offer only a very limited picture of “learning achievement”, especially in the context of a developing country (Ray and Lancaster, 2003). Moreover, Heady (2000) observed that using test scores on reading skills in English language constitutes an inappropriate measure of “learning achievement”. Thus, as specified by Ray and Lancaster (2003), a more appropriate measure of school attainment (achievement) is the Grade-for-Age variable as it measures schooling attainment relative to the child’s age. Based on this, the grade-for-age index was analyzed the effect of child labour on school