The Earlier the Better? Individual Participant Data and Traditional Meta‐analysis of Age Effects of Parenting Interventions

Abstract

Strong arguments have been made for early intervention for child problems, stating that early is more effective than later, as the brain is more malleable, and costs are lower. However, there is scant evidence from trials to support this hypothesis, which we therefore tested in two well-powered, state-of-the-art meta-analyses with complementary strengths: (a) Individual participant data (IPD) meta-analysis of European trials of Incredible Years parenting intervention (k = 13, n = 1696; age = 2-11); (b) Larger, trial-level robust variance estimation meta-analysis of a wider range of parenting programs (k = 156, n = 13,378, M = 2-10) for reducing disruptive behavior. Both analyses found no evidence that intervention earlier in childhood was more effective; programs targeted at a narrower age range were no more effective than general ones.

Meta‐analysis and Individual Participant Data Synthesis in Child Development: Introduction to the Special Section

“…We believe the reader will conclude that the nine focal articles included in the special section (along with Maughan & Barker's, , commentary on Gardner et al., ) very much stand on their own in summarizing and extending knowledge in a variety of substantive developmental domains. Nonetheless, we would emphasize at the outset several important crosscutting themes that tie these articles together and help them collectively speak to the future of cumulative science in the discipline.…”

“…One clear message of the articles presented here is that the quantitative synthesis of developmental data is a domain‐general enterprise . Indeed, the articles featured in this special section cover most of the full range of modern developmental science, including developmental cognitive neuroscience (Yaple & Arsalidou, ), language development (Bergmann et al., ; Quinn & Wagner, ), numerical cognition (Hornburg, Wang, & McNeil, ), social and emotional development (Larzelere et al., ; Verhage et al., ), intervention and prevention science (Gardner et al., ; Leijten et al., ), and even generational‐ and age‐related change in children's stereotypes and behavior (Miller et al., ). In short, it would be a mistake to claim that meta‐analysis is only appropriate for select domains of developmental science.…”

“…Another article featured in this special section that is likely to be the focus of attention and the target of close scrutiny is that of Gardner et al. (). Gardner et al.…”

“…Gardner et al. () report two meta‐analyses that question whether earlier intervention has “value added” compared to later intervention in addressing child behavior problems, concluding that it does not. Maughan and Barker (), in their Commentary on this article, suggest that the time span of the studies covered in the meta‐analyses might miss crucial early years.…”

“…One primary emphasis was on methods of meta‐analysis as applied to developmental questions and we thus welcomed articles illustrating these methods with substantive developmental examples (alongside the publication of extensive electronic supplements to maximize reproducibility and future extension to other domains). In the developmental field specific questions arise, for example, about how to conduct meta‐analyses on cross‐sectional and longitudinal studies (e.g., Larzelere, Gunnoe, & Ferguson, ; Leijten et al., ; Miller et al., ), maximize the quality of causal inferences (Gardner et al., ; Larzelere et al., ; Leijten et al., ), and go beyond bivariate associations to testing more complete and realistic developmental models (Quinn & Wagner, ). Articles in this special section touch on these and related topics.…”