| Ashlesha Datar
RAND Graduate School
Does entering kindergarten at an older age lead to better school performance?
FINAL REPORT
This paper uses data from the Early Childhood Longitudinal Study to estimate the effect of kindergarten entrance age on childrenÕs academic performance. Previous studies do not adequately control for unobservable factors related to academic achievement that are also correlated with entrance age, thereby leading to selection bias in the estimates. This paper uses exogenous variation in birth dates and kindergarten entrance age policies to obtain instrumental variables estimates of the entrance age effect. The impact of delaying kindergarten entrance on childrenÕs performance in the first few months in school and at the end of two years is estimated.
The results indicate that delaying kindergarten entrance by one year leads to a 6.12, 5.4 and 6.4 point increase in math, reading and general knowledge test scores, respectively, in the beginning of kindergarten. After two years of schooling, this initial advantage remains constant for math, increases by just over a point for reading, and reduces by a quarter for general knowledge. The effect sizes associated with a one year delay in entrance on test scores after two years in school are sizeableÑ0.85, 0.78 and 0.62 standard deviations for math, reading and general knowledge, respectively. These estimates are large compared to effect sizes of other educational interventions such as class size reduction. These results imply that younger and older entrants learn math and reading at the same rate during the first two years in school. The impact of delaying kindergarten entrance on academic achievement differs significantly by poverty and disability status. The initial gain from delaying entrance is smaller for poor and disabled children. However, at the end of two years the entrance age effect does not differ by poverty and disability status as older poor and disabled entrants gain more than younger entrants.
The implications of these finding vary depending on the decision-maker. While parents of kindergarteners may be concerned with level differences in achievement, state policy makers or school district officials may care only about the rate at which older and younger entrants learn from school (the Òvalue-addedÓ from schooling). Any attempt to raise the minimum entrance age into kindergarten must also take into account the costs associated with such policies, such as child care costs and forgone wages. Moreover, findings of this paper suggest that benefits of delaying entrance may vary across different population subgroups and therefore states should be cautious before implementing any blanket policies that raise the minimum entrance age for all children.
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