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The decision about when to start school is one of the most important for parents. As women are nowadays much more integrated into the labour market, more and more studies have focused on the importance and quality of pre-school education and investment in education from the early years of life. This is even more relevant for children who are more likely to be exposed to an adverse environment during childhood. This dimension is particularly relevant in a country like Portugal where, despite the decrease in recent years, the rate of children and adolescents at risk of poverty still stands at 28%, according to data from 2017 (the most recent).

The figure below illustrates the return on investment in education over different periods. We can see that as the individual becomes older (age represented on the horizontal axis), the return on that investment (measured on the vertical axis) decreases. That relationship lies behind an important concept in the economics of education called the "Heckman Equation", which advocates strong investment in student education from an early age. James Heckman, a Nobel laureate in economics in 2000, has been one of the main advocates of pre-primary education and has done a lot of work on the return to this level of education.

Cunha et al. (2010) studied how education investments are related at different points in time, concluding that those made at an earlier stage in the student's life show higher returns. They also noted that returns on investments in lifelong learning have a high level of complementarity, i.e. investments in adult life, such as vocational training, have higher returns when there is an initial investment stock in childhood. Symmetrically, investments made in the first years of life will have a higher return over the course of life if they are followed by investments in the following years.

When referring to the return on pre-school education, we can focus on different types of programmes, from those with a more experimental character, which are usually particularly designed for children from disadvantaged families, or those with a more universal character.

Experimental programmes and their impacts

Two of the most famous experimental programmes are the "Perry Preschool Project" (PPP) and the "Carolina Abecedarian Project" (ABC). The former started in the 1960s and the latter in the 1970s, and both of them presented the enormous advantage of following the students who were part of it over the following decades, thus allowing the assessment of not only the short-term impacts, but also the consequences throughout life.

The PPP was designed for African-American children from the state of Michigan (United States of America) between the ages of 3 and 4 coming from families from low educational strata, while ABC was a programme for children between the ages of 0 and 4 developed in North Carolina. For those children, the alternative to not attending those programmes was generally to be cared for at home or in alternative programmes, which in the case of the PPP in Michigan were scarce at the time. In cognitive terms, both programmes have been shown to have had significant and strong effects on the short-term IQ level, around 11 points for both boys and girls. However, part of that effect eventually dissipated in subsequent years, particularly in the early years of primary education. Still, the programmes show impacts on school performance and the labour market in the long term. The PPP increases the probability of completing secondary education for women by about 56 per cent, and the probability of employment for men by 40 per cent. Moreover, the impacts of both projects go beyond the cognitive dimension, leading to a decrease in crime or drug use later in life. A study published in 2006 shows the importance of this non-cognitive dimension during adulthood and in the labour market, particularly in factors such as motivation, persistence, and self-esteem. Counting on these various benefits, a cost-benefit analysis of the PPP programmes concluded that for every dollar invested at age 4 there is a return between 60 and 300 dollars at age 65.

One of the most famous pre-school programmes in the United States is the Head Start programme. Established in 1965, it is aimed at children between the ages of 3 and 5 who are integrated in centres that attempt to develop their cognitive and non-cognitive abilities. The programme also covers the family, with the goal of improving the child's home environment by supporting the parents, who may also receive medical or housing support, in their children's growth. The returns from the Head Start programme, especially in the short term, are heterogeneous and not always positive. However, when we look at the long term, the programme is more robust in reducing obesity at 12 and 13, depression and obesity at 16 and 17, and crime between 20 and 21.

Comprehensive programmes: greater impact on underprivileged environments

When we look at more comprehensive programmes that aim to bring a universal character to preschool education, we find experiences in Norway, Quebec (Canada), and several states in the United States of America 1. One of the main results that emerge from these analyses is that the main impact is on children whose family contexts are most deprived. This is largely explained by the fact that the alternatives available to children from more vulnerable socioeconomic backgrounds are more contrasting with pre-school education programmes.

However, there is another relevant conclusion arising from these experiences of universalisation: the pre-school education programmes which prove to have the greatest impact are those which clearly have a higher quality of learning. In particular, when we focus on the United States, there are pre-school programmes that take place in larger and more organised kindergartens than others. The greatest returns from preschool education are those where students are in these larger and more organised spaces, and which have a positive impact on the child similar to that of time spent with the mother.


Carneiro, P., e Ginja, R., «Long-Term Impacts of Compensatory Preschool on Health and Behavior: Evidence from Head Start», American Economic Journal: Economic Policy, 6(4), 2014, pp. 135-173.

Heckman, J., Stixrud, J., e Urzua, S., «The effects of cognitive and noncognitive abilities on labor market outcomes and social behavior», Journal of Labor Economics, 24(3), 2006, pp. 411-482. 

Heckman, J., Moon, J., Hyeok, S., Pinto, R., Savelyev, P., e Adam, Y., «The rate of return to the HighScope Perry Preschool Program», Journal of Public Economics, vol. 94(1-2), 2010, pp. 114-128. 

Cunha, F., Heckman, J., e Schennach, S., «Estimating the technology of cognitive and noncognitive skill formation», Econometrica, 78(3), 2010, pp. 883-931.

Sneha, E., Garcia, J., Heckman, J., e Hojman, A., «Early Childhood Education», NBER Working Paper No. w21766, 2015. 

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