Are More Intensive Early Intervention Programs More Effective? A Literature Review

Help with Listen Feature Help with Listen Feature

NICHCY’s Structured Abstract 41 describes the following:

Title | Are More Intensive Early Intervention Programs More Effective? A Literature Review

Author | Innocenti, M.S., & White, K.R.

Source Exceptionality, 4(1), 31-50.

Year Published | 1993

Examined the intensity hypothesis, which states that more intensive early interventions have better outcomes for children with disabilities. Three sources of evidence are analyzed: (1) previous reviews of early intervention research; (2) a meta-analysis that included data from 155 children, providing information on intensity and outcomes; and (3) previously reported experimental studies that compared the effects of different levels of program intensity. Based on these combined sources, there was little evidence indicating that more intensive programs lead to better outcomes for children with disabilities. Some limited support exists indicating that more intensive programs may be beneficial for disadvantaged children. (PsycINFO Database Record (c) 2004 APA, all rights reserved)

Prior research on early intervention has concluded that more intense intervention programs produce better outcomes for children than less intensive programs. However, according to the authors, the evidence presented by these previous reviewers is not persuasive because it has been based only on indirect evidence about the “intensity hypothesis.” and none of the studies directly compared programs of different intensities. In addition, the majority of these past reviewers recommended conducting more research using intensity as an early intervention efficacy variable. Consequently, in order to gain additional information about the validity of the intensity hypothesis, the authors conducted a meta-analysis that included all reports on early intervention research that used intensity as an independent variable. They analyzed the results by comparing levels of intensity based on whether the interventions were home-visit, center-based, or home visit vs. center-based.

Research Questions
Are more intensive early intervention programs more effective?

Research Design

  • Number of Studies Included | 20
  • Number of Subjects | N/A
  • Years Spanned| 1969-1991

Research Subjects
Children receiving early intervention services either in a home-based or a center-based setting.

Age/Grade of Subjects
From 0 to 62 months

Specified Disability
Disabled and disadvantaged children


  • Home- visit intervention
  • Center-based intervention
  • Home-visit vs. center-based intervention

Duration of Intervention

  1. The seven studies on home visit interventions compared intensities on a ratio of approximately 2:1 and the number of hours per week of intervention in the more intensive group ranged from .5 to 3.0
  2. The number of hours per week of intervention in the center-based intervention programs ranged from 7.0 to 40.0
  3. The number of hours per week in the home-visit versus center-based programs intensity comparisons ranged from 5.0 to 40.6


  1. The results from the studies that examined home visit intervention, suggest that the proposal that more is better needs to be examined.
  2. Just two studies collected data on family functioning, although it has been suggested an area in which home-visit intervention may have a strong impact.
  3. There is no convincing evidence that children in more intensive center-based programs benefit more than those in less intensive programs.
  4. The strongest studies in the center-based category, did not find benefits related to more intensity.
  5. Since the studies in the home- visit vs. center-based category varied in intervention activities, training of intervention providers, the accessibility of interaction with other children, and the philosophical approach; it was less clear if the group differences observed could be attributed to the differences in hours per week of intervention or to other factors.
  6. The results of the 13 studies conducted with children with disabilities do not support the intensity hypothesis.
  7. Some little evidence suggests that disadvantaged children may be more readily influenced by the intensity of intervention than disabled children.

Combined Effects Size

Studies conducted with children with disabilities:

  1. The effect sizes for home based interventions ranged from -.02 to .09
  2. The effect sizes for center-based interventions ranged from -.11 to 1.41
  3. The effect sizes for home-visit versus center based-based interventions ranged from -.52 to .38

Studies conducted with economically disadvantaged children:

  1. The effect sizes for the two studies of home based interventions were .22 and .57
  2. The effect sizes for the one study on center-based intervention was .80
  3. The effect sizes for home-visit versus center-based intervention ranged from -.14 to 1.57

Even though there is a lot of support in the literature about the hypothesis that more intensive programs are better, there is not sufficient evidence to support this claim. Future research will be most useful if it addresses the following issues:

  1. In addition to measuring IQ, researchers should consider measuring other developmental outcomes in relation to program goals, as well as other areas such as adaptive functioning, social skills, and academic survival skills.
  2. Parent and family functioning are variables that should be further investigated. There is a need to examine interactions between family variables and types of intervention.
  3. Since intensity may represent a variety of intervention differences, the construct of intensity should be better defined to avoid confusion by other program variables.
  4. There is a need of more comparative studies of high methodological quality to better understand the impact of different levels of intensity.
  5. The effects of more intensive early intervention programs could not be evident until the child enters school, for that reason; there is a need of longitudinal studies than can provide longitudinal data as regards to efficacy.


* 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.

Back to top

NOTICE: NICHCY is going away, but its resources are not. Find hundreds of legacy NICHCY publications, as well as our training curriculum on IDEA 2004, in the Center for Parent Information and Resources' Library at This website will remain available until September 30, 2014. After that date, web visitors will be automatically redirected to