Related to
Early Years

Written by Keryn O’Neill, MA, PGCertEdPsych, Knowledge Manager


The attempts to use evidence when developing policy to enhance outcomes for New Zealand’s children are to be applauded. Research can certainly be a very useful tool in determining which of the multiple options facing Government are likely to effectively contribute to improved wellbeing for children. However, like the tools used by the Kiwi DIY-er, correct use is necessary for a positive result.

Inaccurate interpretations of research can occur, particularly when relying on reviews rather than the original research. One of the most publicised early intervention studies is The High Scope/Perry Preschool project, which, as others have noted previously, has been frequently misinterpreted to advocate for extending centre-based early childhood education (ECE). The following extract from the recent Report of the Health Select Committee is an example of this:

“The High/Scope Perry Preschool Study, which began in the 1960s, has determined the short- and long-term effects of a high quality preschool education programmes (sic) for young children living in poverty.”

This paper will briefly describe the original Perry Preschool Project, clarify what can be learned from this research, as well as increasing clarity about what cannot be extrapolated from its findings. 

The Perry Preschool Study

The study began in Ypsilanti, Michigan in 1962 and included a total of 123 African American children from low income families, who were randomly assigned to treatment or control groups. The programme’s goal was the improvement of the children’s academic achievement. IQ test scores of the children ranged from 70 – 85, in other words they ranged from below average to delayed levels of intelligence. Children began the programme at three or four years of age and it operated for eight months each year. The children were studied in five ‘waves’ with the first group beginning when they were four, and subsequent groups beginning at 3 years of age. 

The intervention involved 2.5 hours of centre-based instruction on weekday mornings, a weekly teacher home visit of 1.5 hours’ duration, as well as monthly parent group meetings. The focus of the home visit was on the child and the parent-child relationship, in particular, supporting the mother to implement the child’s educational curriculum in the home.

Teachers at the centre had child development training, all had Masters’ degrees, and they were paid 10% above the standard pay scale of the time. Teachers received high levels of supervision and ongoing training.

Findings of the Perry Preschool Study

One of the strengths of this research was its strong emphasis on ongoing evaluation of outcomes, and there certainly were many positive outcomes. It should be noted that the longitudinal results are based upon outcomes for 58 children who remained in the intervention group.

Children receiving the intervention were significantly less likely to have teacher reports of personal or school misconduct. In adulthood, those who had been in the intervention were more likely to have stable families, higher earnings, have completed more formal education, and have better health. They were also more likely to own their own home, be employed, and less likely to have been arrested or be reliant on welfare payments. The benefit in terms of reduced criminal activity was large and there was a reduced rate of teenage pregnancy. 

Financial analyses indicated that this investment made in early childhood had a major financial return to society. 

What Does it Mean?

A specific group of at-risk children, aged 3 – 4 years of age, who received weekly family education and support, and high quality ECE, including small groups and highly trained teachers, for 12.5 hours per week, for eight months of the year, were more likely to have multiple positive outcomes in adulthood.

The above paragraph needs to be understood in its entirety and no single component can be used in isolation whilst claiming to be informed by the research.

What Does it NOT Mean?

There are a number of conclusions often attributed to the Perry Preschool research which are in fact not supported by the study. Some of these are noted below.

  • The Perry Preschool study does not claim to tell us anything about the effects of ECE on children aged from birth to 3 years of age, as its participants were all 3 or 4 years old. Therefore, this study cannot be used to support children under 3 years attending ECE.
  • It does not indicate that ECE, on its own, is an effective intervention as it was combined with family intervention, which could have had equal or greater effect on the positive outcomes achieved. Therefore, Perry Preschool cannot be used to globally endorse ECE as an intervention to improve children’s outcomes.
  • The Perry Preschool project was staffed by highly qualified and trained teachers who received ongoing supervision and training. Their outcomes cannot be equated with those from the largely commercially-oriented New Zealand ECE environment in which only 50% of staff may have any qualifications. 
  • The children in the study attended for 12.5 hours per week, therefore it tells us nothing about the effects of being in ECE for up to 20 hours per week and cannot be used to support increased hours in ECE


  1.  Campbell et al., 2001
  2. Fergusson et al., 2011; Fergusson et al., 2005; Zigler & Styfco, 1994
  3. Health Committee, 2013, p.22
  4. Zigler & Styfco, 1994
  5. Schweinhart et al., 2005, cited by Muennig et al., 2009
  6. Campbell et al., 2001
  7. Schweinhart et al., 1985
  8. Clarke & Campbell, 1998; Zigler & Styfco, 1994
  9. Schweinhart & Weikart, 1993, cited by Zigler & Styfco, 1994
  10. Clarke & Campbell, 1998
  11. Schweinhart et al., 2005, cited by Muennig et al., 2009
  12. Zigler & Styfco, 1994
  13. Schweinhart et al., 1985
  14. Zigler & Styfco, 1994
  15. Schweinhart et al., 1985; Zigler & Styfco, 1994
  16. Schweinhart et al., 1993, cited by Clarke & Campbell, 1998
  17. Muennig et al., 2009; Weikart, 1998
  18. Schweinhart et al., 1993, cited by Campbell et al., 2001; Clarke & Campbell, 1998; Weikart, 1998
  19. Temple & Reynolds, 2007
  20. Schweinhart et al., 1985
  21. Weikart, 1998


For the reasons cited above, the recommendation to increase ECE for babies and children from birth to 3 years cannot claim to be based on the evidence provided by this study.

The move towards cross party agreement on investment in our youngest children is a hugely positive step for NZ’s future. A commitment to accurately applying the available evidence will ensure this investment is maximised.


Campbell, F. A., Pungello, E., Ramey, C. T., Miller-Johnson, S., & Burchinal, M. (2001). The development of cognitive and academic abilities: Growth curves from an early childhood educational experiment. Developmental Psychology, 37(2), 231-242. 

Clarke, S. H., & Campbell, F. A. (1998). Can intervention early prevent crime later? The abecedarian project compared with other programs. Early Childhood Research Quarterly, 13(2), 319-343. 

Fergusson, D. M., Boden, J. M., & Hayne, H. (2011). Childhood Conduct Problems. In P. Gluckman & H. Hayne (Eds.), Improving the Transition: Reducing Social and Psychological Morbidity During Adolescence (pp. 59-78). Auckland, NZ: Office of the Prime Minister’s Science Advisory Committee.

Fergusson, D. M., Horwood, L. J., Grant, H., & Ridder, E. M. (2005). Early Start Evaluation Report. Christchurch, NZ: Early Start Project Ltd Retrieved from

Health Committee. (2013). Inquiry into improving child health outcomes and preventing child abuse with a focus from preconception until three years of age. Wellington, NZ: New Zealand House of Representatives Retrieved from

Muennig, P., Schweinhart, L., Montie, J., & Neidell, M. (2009). Effects of a prekindergarten educational intervention on adult health: 37 year follow-up results of a randomized controlled trial. American Journal of Public Health, 99(8), 1431-1437. 

Schweinhart, L. J., Berrueta-Clement, J. R., Barnett, W. S., Epstein, A. S., & Weikart, D. P. (1985). Effects of the Perry Preschool program on youths through age 19: A summary. Topics in Early Childhood Special Education, 5(2), 26-35. 

Temple, J. A., & Reynolds, A. J. (2007). Benefits and costs of investments in preschool education: Evidence from the Child-Parent Centers and related programs. Economics of Education Review, 26(1), 126-144. 

Weikart, D. P. (1998). Changing early childhood development through educational intervention. Preventative Medicine, 27, 233-237. 

Zigler, E., & Styfco, S. J. (1994). Is the Perry preschool better than Head Start? Yes and no. Early Childhood Research Quarterly, 9, 269-287.