Outcome of the Early Childhood Education in the CHDS Cohort

Publication Details

This report examines the outcomes of attendance at early childhood education (ECE) amongst members of the Christchurch Health and Development Study (CHDS) birth cohort, with a particular focus on the potential benefits of ECE attendance for longer term outcomes in adolescence and young adulthood. The CHDS is a longitudinal study of a birth cohort of 1265 children who were born in Christchurch during mid-1977. As part of the study information has been gathered on patterns of ECE attendance and a wide array of cognitive, educational, social, behavioural, socioeconomic and psychosocial outcomes over the life course. This report examines the associations between ECE attendance between ages 2-5 years and outcomes to age 30. The report is presented in six chapters.

Author(s): John Horwood, Geraldine F.H McLeod, University of Otago, Christchurch. Report prepared for the Ministry of Education.

Date Published: June 2017

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Executive Summary


Chapter 1: Introduction

This chapter provides a brief background and overview of the existing literature on the outcomes of ECE. The aim is to summarise the evidence for benefits of ECE attendance across a range of functional domains, and document wider research limitations. It is noted that while there is general agreement as to the value and benefits of ECE for child developmental outcomes, particularly in the cognitive/educational and social/behavioural domains, the evidence base has a number of limitations. These include: lack of robust evidence on longer term outcomes of ECE across most functional domains; a lack of good population based studies of the outcome of ECE; questions over the extent to which the findings of a literature dominated by studies of selected populations or programmes targeted at high risk or disadvantaged groups will translate to the wider New Zealand population context. This suggests the need to supplement review of the evidence by local research relevant to the New Zealand setting.

Chapter 2: Methods

This chapter provides a brief overview of the study design; access to a detailed description of the measures used in the study including the assessment of ECE attendance, life course outcomes and covariate factors; together with a summary of the statistical methods and effect size measures used in the report.

Chapter 3: Attendance at Early Childhood Education

This chapter describes the pattern of attendance at early childhood education (ECE) in the cohort from age 2-5 years and the social, family and individual factors associated with ECE attendance. Findings showed:

  1. Overall participation in ECE was high: 94.6% of the cohort had attended some form of ECE over the three year period, with the great majority (85%) attending for at least one year and nearly one third attending for more than two years. The predominant forms of ECE service attended were Kindergarten and Playcentre.
  2. There was clear evidence of socio-economic and related disparities in the uptake of ECE. In particular, uptake of ECE was lowest amongst children from families characterised by socio-economic disadvantage (low parental education, low SES, single parent families); children from larger families; children with poorer quality early mother-child interaction; children from Māori and Pasifika families; and children who exhibited early behavioural difficulties.
Chapter 4: Associations between Duration of ECE Attendance and Later Outcomes

This chapter examines the associations between duration of ECE attendance (none, <1 year, 1-2 years, 2-3 years) and later child, adolescent and adult functional outcomes. The associations are assessed both before and after adjustment for the prior childhood social and family and contextual factors identified in the previous chapter as being associated with ECE attendance. This analysis leads to the following conclusions:

  1. At the bivariate level duration of ECE attendance was associated with a wide range of measures of cognitive, academic, socioeconomic and social/behavioural functioning. In all cases these associations reflected increasing benefit with increasing duration of ECE.
  2. Statistical adjustment for prior social, family and individual factors correlated with ECE attendance explained a substantial component of the observed outcome associations in these domains, and for the majority of outcomes examined the adjusted associations were both practically and statistically non-significant.
  3. Nevertheless for two domains (cognitive functioning and educational/academic attainment) many associations were robust to control for confounding, consistent with benefits of ECE attendance for some aspects of verbal and numerical reasoning, attainment of high school qualifications and academic success up to age 30. These benefits were also reflected in the adjusted associations for a small number of other outcomes including individual socioeconomic well-being at age 30 (participation in paid employment, personal income, occupational status) and adolescent social/behavioural adjustment (teenage parenthood, adolescent offending).
  4. Any impact of ECE attendance on these outcomes after adjustment for confounding was comparatively modest. Duration of ECE attendance accounted for between 0.2-0.9% of the variance in outcomes after adjustment. Values of Cohen's d comparing outcomes for children who received 2+ years ECE with those for children who never attended ECE were in the small to moderate range (d=0.22 to d=0.39).
Chapter 5: Supplementary Analyses

In this chapter the analysis is extended to examine two issues:

  1. The extent to which the above findings were robust to alternative measures of ECE attendance including: (i) ECE attendance at age 4-5 years and (ii) time spent in ECE at age 4-5 (<15 hours per week, 15+ hours per week). Findings showed consistent evidence of small to moderate effect size benefits for cognitive/academic outcomes across all measures of ECE attendance (d=0.12 to 0.39). The benefits for academic attainment appeared slightly larger for those who spent more time (hours per week) in ECE (median d=0.31 for 15+ hours/week; median d =0.21 for <15 hours per week).
  2. The extent to which there was evidence for differential effects of ECE attendance on later outcomes across different subgroups of the cohort defined on the basis of childhood socioeconomic disadvantage, parental education, child ethnicity or gender. Findings showed no evidence of differential effects of ECE across subgroups for any outcome or measure of ECE attendance.
Chapter 6: Discussion

This chapter provides a summary of study findings and discussion of the potential implications of the research. The key findings with respect to the outcomes of ECE attendance are that for this cohort:

  1. Attendance at ECE was associated with robust small to moderate effect size benefits for later cognitive and academic outcomes over the life course.
  2. These benefits were apparent at least up to age 30, and showed no evidence of declining with age.
  3. There was evidence of increasing benefit with increasing duration of ECE or time spent in ECE (hours per week).
  4. The benefits of ECE attendance were similar regardless of childhood socioeconomic status, parental education levels, ethnicity or gender.

The implications of these findings are discussed against the historical context in which the CHDS data were collected, the current policy framework for ECE and the existing evidence base on benefits of ECE. Potential limitations of the study are highlighted including: the substantial changes in ECE service provision and uptake and the ECE policy framework since the 1980s; changes in the education sector, qualifications framework, school retention and related matters; inability of the study to address issues around ECE attendance for under two-year-olds; and other issues.

It is suggested that despite the dramatic changes in the ECE sector and wider education system over the past 30+ years there is no reason to believe that similar cognitive/educational benefits of ECE attendance would not be observed for more recent cohorts of New Zealand children. However, there remains a need for further research. The findings also reinforce current policy efforts to eliminate sources of socioeconomic and ethnic disparities in access to and uptake of ECE services.

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