The downturn in the global economy is leading to big cuts in public expenditure in most areas. Policy makers are faced with difficult decisions about how and where to spend.

In this context, the idea of investing in services for particular groups of vulnerable children to secure a return for the state and taxpayer is garnering much support.

Nobel-prize winning economist James Heckman gave the argument some authority in 2006 when he made a strong case based on the economic costs of childhood poverty and the benefits of intervening early. His was one of several important contributions to the economic argument for providing preschool child care for children from low income families.

The logic goes as follows. Children from low-income families are more likely to struggle when they start school. This disadvantage persists as they progress through school and is aggravated by lower achievement in reading and maths. This in turn hinders their prospects when they eventually enter the job market.

Their early disadvantage follows them into adulthood. Providing high quality preschool child care helps to break the chain – and the damaging family cycle – by preparing children from low income backgrounds for school and narrowing the attainment gap between them and their more affluent peers.

This is by now much more than an elegant theory: evidence from experimental trials of model programs such as High/Scope Perry Preschool has established a causal link.

Unfortunately, children’s services systems have not yet found a reliable means to scale up the quality delivery of model programs which provide something more durable than basic childcare. Until they have the means, the evidence – no matter how compelling – is not by itself enough to sway policy makers.

Recent work by Eric Dearing at the Lynch School of Education, Boston, and colleagues at Harvard and Samford has shed light on this complex topic analyzing data from the US NICHD Study of Early Child Care and Youth Development.

Their report to the journal Child Development confirms findings established in other studies that higher quality child care promotes the maths and reading achievement of low-income children. But they provide some additional insights particularly relevant to policy makers.

First, they find that more is better. The more sessions in higher quality child care. the weaker the link between family income and achievement in middle childhood. So much so, that there comes a point when the gap between poor children and their more affluent peers appears to close.

Second, when it comes to quality, the best is not necessarily better. They suggest that “above average” quality childcare seems to deliver benefits sufficiently well.

Third, that although the the biggest and most cost effective gains accrue from good contact with the poorest children, there are also benefits for the less poor.

The authors conclude that “given these results, maximizing public policy benefits relative to costs may require investing primarily in higher quality care for families at the low end of the income distribution”.

They suggest that the finding may be “relevant for discussions on universal versus targeted preschool and child-care policy initiatives”.

See: Dearing E, McCartney K. and Taylor B (2009) “Does Higher Quality Early Child Care Promote Low-Income Children’s Math and Reading Achievement in Middle Childhood?” Child Development, 80, 5 pp 1329-1349.

[See also: The pros and cons of early years programs – where to start!]