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Version 1.1 – Updated August 2021

Adopted vs. non-adopted children

Overview

  • Influence: Adopted vs. non-adopted children
  • Domain: Home
  • Sub-Domain: Family structure
  • Potential to Accelerate Student Achievement: Likely to have positive impact
  • Influence Definition: These studies compare the performance of children who have been adopted with those not adopted.

Evidence

  • Number of meta-analyses: 3
  • Number of studies: 150
  • Number of students: 0
  • Number of effects: 112
  • Effect size: 0.25

Meta-Analyses

Meta-Analyses
Journal Title Author First Author's Country Article Name Year Published Variable Number of Studies Number of Students Number of Effects Effect Size
Journal of Clinical Child Psychology Wierzbicki USA Psychological adjustment of adoptees: A meta-analysis 1993 Adoptee vs. nonadoptive achievement 66 0 31 0.13
Psychological Bulletin van Ijzendoorn, Juffer, Poelhuis Netherlands Adoption and cognitive development: a meta-analytic comparison of adopted and nonadopted children's IQ and school performance 2005 Nonadopted vs. adopted children 55 0 52 0.19
Journal of Speech, Language, and Hearing Research Scott, Roberts, & Glennen USA How well do children who are internationally adopted acquire language? A meta-analysis 2011 Language skills of internationally adopted children 29 0 29 0.44
TOTAL/AVERAGE 150 0 112 0.25

Confidence

The Confidence is the average of these four measures, each divided into five approximately equal groups and assigned a value from 1 to 5 based on the following criteria:

  • Number of Meta-analyses
    • 1 = 1
    • 2 = 2–3
    • 3 = 4–6
    • 4 = 7–9
    • 5 = 10+
  • Number of Studies
    • 1 = 1–10
    • 2 = 11–50
    • 3 = 51–200
    • 4 = 201–400
    • 5 = 400+
  • Number of Students
    • 1 = 1–2,500
    • 2 = 2,501–10,000
    • 3 = 10,000–20,000
    • 4 = 20,000–100,000
    • 5 = 100,001+
  • Number of Effects
    • 1 = 1–100
    • 2 = 101–300
    • 3 = 301–600
    • 4 = 601–1,200
    • 5 = 1,200+
Confidences
Number of Meta-Analyses Number of Studies Number of Students Number of Effects Overall Confidence
Confidence Factor 2 3 1 2 2
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