Title | When Should We Begin? A Comprehensive Review of Age of Start in Early Intervention
Author | Kim, Y-W., Innocenti, M., & Kim, J-K
Source | South Korea, ERIC (Education)
Year Published | 1996
This literature review examines whether verifiable evidence supports the supposition that early interventions result in better child developmental outcomes than later interventions for disadvantaged children with disabilities. First, existing reviews of the literature on the “earlier is better” supposition were examined. Second, a meta analysis on a database of articles that allowed exploration of the concept of early intervention was conducted. Finally, research reports which directly attempted to address the “earlier is better” supposition were reviewed. The paper concludes there is mild evidence to support the belief that earlier interventions lead to better outcomes for children with disabilities or from disadvantaged backgrounds. The evidence to support this claim is not overwhelming, however, and other intervention factors (such as location of services and severity of child risk) interact with the factor of starting age. Relatively little research was found which was designed to adequately and directly answer the “earlier is better” supposition.
Even though the belief that “earlier is better” is widely accepted in regard to children entering early intervention programs; there is almost non-existent evidence to support this supposition. Previous studies on the “earlier is better” assumption are not conclusive on whether age when intervention begins is related to the effectiveness of intervention. These studies were not conclusive because they were flawed by little empirical data, methodological problems and inconsistent conclusions. Also, it is clear that the data past reviewers considered was based only on indirect evidence about the issue of age entry. The purpose of this meta-analysis was to find out is there is evidence to support the claim that early interventions produces enhanced developmental outcomes than later interventions for disadvantaged children or children with disabilities.
Is there evidence to support the claim that early interventions result in better developmental outcomes than later interventions for disadvantaged children or children with disabilities?
Review of existing literature, Meta-Analysis*
- Number of Studies Included | 80
- Number of Subjects | N/A
- Years Spanned | 1970-1996
Children with disabilities and children who were economically disadvantaged.
Age/Grade of Subjects
Various disabilities and children who were economically disadvantaged.
Early Intervention programs.
Duration of Intervention
- Overall, children benefit from early intervention begun at any age.
- There is only mild evidence to support the claim that earlier interventions lead to better outcomes for children with disabilities or from disadvantaged backgrounds.
- Data suggested potential interaction of age-at-start with child-risk factor, location of services, and severity of child risk.
- Meta-analysis data had wide variability in study outcomes for children less than 18 months.
- 85% of the meta-analysis studies had differences of 3 months or less between program entry for the different comparison groups. This could not be adequate for truly examining questions regarding early is better issues.
- Primary research is mixed regarding the benefits of starting earlier. This research is very limited.
Combined Effects Size
Age Disabled Disadvantaged
<18 months 0.18 0.75
18-36 months 0.87 0.20
37-48 months 0.39 0.30
Future research should address the following issues:
- In addition to IQ, researchers should measure other child outcomes like: adaptive functioning, social skills, and academic survival skills, because they could have an impact on future functioning.
- Researchers need to include measures of parent and family functioning in their research, and examine interactions between family variables and types of intervention.
- Comparative studies of high methodological quality are very important to understand the impact of different age entry and they will facilitate analysis of age entry and other program variables.
* Meta-Analysis | A widely-used research method in which (1) a systematic and reproducible search strategy is used to find as many studies as possible that address a given topic; (2) clear criterion are presented for inclusion/exclusion of individual studies into a larger analysis; and (3) results of included studies are statistically combined to determine an overall effect (effect size) of one variable on another.