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Systematic Review
To review and analyse the research evidence on components of successful early education program strategies for low-income children
The meta-analysis (search period through November 2013) met Community Guide systematic review standards in terms of intervention definition, outcome assessment, study design and execution evaluation, and synthesis of effect estimates. To maximize validity, researchers only included studies with high quality design and good quality of execution. The report included educational outcomes (i.e., standardised test scores, high school graduation, grade retention, and assignment to special education) as well as social and health-related outcomes (i.e., crime, teen birth, self-regulation, and emotional development). Separate analyses were conducted for state and district programs (combined), the federal Head Start program, and model programs, such as the Perry Preschool and Abecedarian programs
In the studies included in the meta-analysis, some outcomes were assessed shortly following program completion, and others were assessed when students were older.
All effects were in a favourable direction for each program type (for which they were evaluated), but not all effects were statistically significant at the 0.05 level. The outcomes relevant to this map have been extracted below:
- Standardised achievement tests – significant beneficial effects were found for all three program types:
State and district: 0.32 Standard Deviation (SD) (95%CI 0.25, 0.38)
Head Start: 0.17 SD (95%CI 0.12, 0.23)
Model programs: 0.57 SD (95%CI 0.24, 0.81)
- Grade retention –non-significant beneficial effects were found for all program type:
State and district: -0.39 SD (95%CI -0.26, 0.19)
Head Start: -0.08 SD (95%CI -0.34, 0.19)
Model programs: -0.46 SD (95%CI -0.96, 0.03)
- Self-regulation – a statistically significant positive effect was found for state and district programs; a nonsignificant benefit was shown for Head Start, and no studies of model programs evaluated this outcome:
State and district: 0.23 SD (95%CI 0.12, 0.33)
Head Start: 0.16 SD (95%CI -0.09, 0.41)
- Emotional development – effects were negligible and statistically non-significant for state and district programs and Head Start programs, and no studies of model programs evaluated this outcome:
State and district: 0.04 SD (95%CI -0.08, 0.17)
Head Start: 0.03 SD (95%CI -0.07, 0.13)
The meta-analysis assessed the persistence of program effects on standardised achievement tests in combination with outcomes such as intelligence quotient (IQ). Among several models evaluated, the statistical model that best fit the long term data was a power function in which there was a rapid decrease of effectiveness following the conclusion of the program, followed by a more gradual decline in later years. An assessment of the difference in rates of decline in achievement versus IQ indicated no statistical difference (N. Kay, personal communication, November 12, 2014). When program participants were 9 years old, there remained a statistically significant program benefit; the power curve indicated slow subsequent decline in effect.
There was suggestive, but not statistically significant, evidence for two program characteristics that promoted greater effects on achievement outcomes: instructors' education and quality scores. Programs that hired teachers who had at least a bachelor's degree showed greater effects on student standardised achievement, as did programs with higher program quality scores on the Early Childhood Environmental Rating Scale – a scale that includes many evidence-based elements. Data were insufficient to determine the most effective class size, hours, duration, program foci, or the possible benefit of additional components (e.g., health care, parental involvement, or meals).
This CPSTF report concludes that:
- There is strong evidence that center-based early childhood educational programs improve educational outcomes.
- Program effects on standardised achievement tests decline over time, but persist.
- There is sufficient evidence that center-based early childhood educational programs improve social and health outcomes.
- All three reviewed program types are effective (state and district programs, Head Start programs, and model programs) in improving diverse educational, social-, and health-related outcomes.