Trends of Child Achievement Gaps Between the Rich and the Poor – Comparison Between the 1998 and 2010 Kindergarten Cohorts

Background and Purpose: A large amount of research has explored the association between poverty and child academic achievement. However, we have little evidence about the extent to which the achievement gaps between rich and poor children have changed over time. For the last decade, income inequality has been growing significantly. The 2008 Financial Crisis hurt the poor more than the wealthy, further sharpening the inequality. Since income inequality plays a significant role in affecting child cognitive development, we expect that achievement gaps to be widening. On the contrary, existing studies stated that investments in children, especially in low-income children, have been rising prominently, suggesting that achievement gaps may instead be narrowing. 

How did child achievement gaps between the rich and the poor change for the last decade? In order to answer this question, the study used the two nationally representative datasets of Early Childhood Longitudinal Study, Kindergarten Class of 1998-1999 (ECLS-K: 1998) and the Early Childhood Longitudinal Study, Kindergarten Class of 2010-2011 (ECLS-K: 2010) and examined the changes of achievement gaps between the rich and the poor of 1998 and 2010 kindergarten cohorts.

Methods: The study used data from the first two waves of data collection of the ECLS-K: 1998 (N=14,800) and ECLS-K: 2010 (N=13,800). Children were categorized into three groups – low-income group (children from families at or below 10th percentile of income distribution), high-income group (children from families at or above 90th percentile income distribution), and in-between income group (children from families above 10th percentile and below 90th percentile income distribution).

The dependent variables in the study include child reading Item Response Theory (IRT) score and math IRT score. The study also controlled child and family demographic variables, such as child gender, age at assessment, race/ethnicity, low birth weight, parent education, family type, and primary home language.

The study used the Difference in Difference (DD) statistic research method. It pooled the two datasets and omitted the high-income children group as a reference. The interaction of low-income children group and cohort dummy was added in the regression, which indicated the change of high- and low-income achievement gap from 1998 to 2010.

Results: Both the descriptive results and multivariate regression results show that the high- and low-income child achievement gaps declined from 1998 to 2010. According to the multivariate results, reading and math achievement gaps narrowed by 0.131 standard deviations and 0.118 standard deviations, respectively. Compared to the changes in reading, math had relatively small and less significant changes. Potential explanations for the narrowing achievement gaps include both the increased public and private investments in children, especially for low-income children.

Conclusions and Implications: The study found that even though income inequality had been growing, child preschool achievement gap was narrowing from 1998 to 2010, suggesting that protective factors, such as rising investment on children, might buffer the negative influence of increasing income inequality, which may provide significant implications for early childhood policy and interventions. Future decomposition research is needed to test the contribution of rising investments on narrowing the achievement gaps.