Excerpts from the commentary:
As a member of the Peripheral Review Group, I have serious reservations about the interpretation of results, and therefore the conclusions drawn, in the recently published Early Years Review entitled "What is known about the long-term economic impact of centre-based early childhood interventions?" (Penn et al., 2006). Let me explain.
The Review concludes that we do not know very much (see the Summary and Chapter 5 &em; Conclusions and Implications). We do know from the studies reviewed that the children involved in the specific interventions were better off, but it is concluded that we cannot make any inferences to other populations based on this evidence. We are told that "there may well be long-term outcomes from early childhood interventions…." (p. 4), but that "the widespread, international, use of the most favourable headline findings, and in particular of the Perry High/Scope study, is unjustified." (p. 3). We also receive considerable warnings about the difficulty of using longitudinal studies, and the weaknesses of cost-benefit analysis. However, the authors are unable to answer the question "Do early childhood interventions save money over the long term?" (p. 3) with a positive response.
This reticence on the part of the authors is surprising. There is now a very substantial literature on the positive effects on cognitive and language development of early childhood education (Vandell, 2004; Cleveland, 2005). The evidence about effects on social competence and behaviour is more mixed, but generally very positive effects on behaviour have been found for children from low-income families. In particular, the evidence from experimental studies of early childhood interventions has been strongly positive (Karoly et al, 1998). Further, there have been very good studies of the impacts on children of the large Head Start program in the United States, which serves close to a million children per year in 20,000 centres (Currie and Thomas, 1995, 2000; Garces, Currie and Thomas, 2002). Head Start has been found to have long-term and substantial positive impacts on children, through to adulthood.