Long-run benefits from high-quality preschool


A recent research project suggests that higher quality in preschool is associated with a small positive long-term impact on children’s abilities. The results suggest that there may be potential in developing preschool and strengthening the links between preschool and primary school. The project is based on a cohort of Danish children who finished primary school in 2008.

Social science research is increasingly acknowledging the importance of early childhood development in forming children’s cognitive and non-cognitive abilities. One way of countering negative social heritage is to give children from all backgrounds access to high-quality daycare. Along with the other Nordic countries, Denmark has a tradition for having more than 90% of 3-6 year-olds enrolled in preschool. In a joint project between researchers at SFI, the Danish Institute of Governmental Research (AKF), Aarhus University and Maastricht University, we investigate whether preschool quality is important for children’s cognitive and language development at the end of elementary school (age 16).

Our research questions are the following: Are children’s cognitive skills correlated with preschool quality? And can we establish a causal relationship between preschool quality and individual long-term child outcomes? Child outcomes are measured as test scores from final (9th grade) elementary school exams in written Danish.

Our data material is based on Danish register data in which preschool children are linked to their preschool and preschool teachers. Based on these unique data, we generate five main quality indicators of preschools: 1) the staff-to-child ratio (number of teachers per child), 2) the share of male staff in the preschool, 3) the share of pedagogically trained staff in the preschool, 4) the share of non-native staff, and 5) the stability of the staff (inverse staff turnover in the preschool). Needless to say, these indicators far from capture all aspects of quality in preschools, but the merits of our chosen indicators lie in that they are objectively measurable and comparable across preschools and municipalities.

After having controlled for child background factors, we find that a higher number of staff members per child, a higher share of male staff, a higher share of staff with a pedagogic education, and a higher share of non-native staff lead to significant – albeit numerically modest - improvements in children’s test results in Danish at the end of 9th grade. The main effects for a unit change in the five quality indicators range around 2-4 standardized points in the OLS estimations, and somewhat larger, namely 0-19 standardized points in the IV estimations. This implies that an increase in e.g. the staff-to-child ratio of around one standard deviation (corresponding to a 30% increase in teacher resources) implies an increase in the standardized score of 0.2-0.7. For the average pupil with an average test score at around 6.5 on the Danish grade scale, this translates into an increase in grades of 0.01-0.05. Hence, a substantial increase in teacher resources is associated with a rather modest increase in grades. However, the fact that we find long-lasting effects of pre-school even after 10 years of schooling is quite remarkable in an international context.

We also analyse which groups of children benefit most – and least – from high-quality daycare. We find evidence that boys benefit more from preschool quality than girls. Moreover, non-native children benefit from a lower staff turnover. Finally, our empirical evidence suggests that peer group matters; the pre-school’s share of children with parents with low levels of education is strongly and negatively related to child outcomes.

The empirical model is estimated by ordinary least squares estimation (OLS) and instrumental variables (IV) estimation. For most quality indicators, IV estimates show significant positive effects, which are numerically higher than the OLS estimates.

Long-Run Benefits from Universal High-Quality Pre-Schooling. By Robert Bauchmüller, Mette Gørtz and Astrid Würtz Rasmussen. 2011.

AKF Working Paper 2011(2), 

CSER Working Paper No. 0008, 

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