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ABSTRACT
Over the past 2 decades, a growing number of randomised controlled trials have assessed the impact on children’s language skills of interventions encouraging parents to read books to their offspring. We present the results of a meta-analysis of the impact of 30 such interventions. Results indicate that they are often ineffective, and that only one specific methodology (dialogic reading) displays systematically positive impacts. Moreover, effective interventions display weaker impacts on low-socioeconomic groups, thus raising equity issues. Our systematic analysis of the research designs of these studies points at three major weaknesses. First, only short-term outcomes are measured, and, even within such a narrow time window, we find indications that treatment impacts fade out. A second limitation concerns the limited range of outcomes measured (receptive or expressive vocabulary). Finally, these studies display low external validity (ad hoc sampling, small sample sizes, lack of multi-site experiments, scant evidence outside Anglo-Saxon countries).
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes on contributors
Carlo Barone is full professor at Sciences Po, Paris. He is the co-director of the research axis on educational policies of the Laboratory for the Interdisciplinary Evaluation of Public Policies (LIEPP). His research focuses on educational inequalities, social mobility, and impact evaluation studies of educational policies.
Emilio Chambouleyron is a postgraduate student of Political Science at the Catholic University of Cordoba (Argentina). His research interests focus on education and public policy evaluation.
Reka Vonnak is a postgraduate student at the University of Glasgow focusing on quantitative social research and spatial analysis, applied to the analysis of educational inequalities.
Giulia Assirelli is an independent researcher collaborating with several public and private institutions. Her research interests deal with the evaluation of public policy especially in the areas of education and training.
Notes
1 Quasi-experimental designs (such as regression discontinuity and differences-in-differences) are rare in the literature on SBR as they involve dubious assumptions, such as instrumental variable regressions based on dubious instruments (Kalb & van Ours, Citation2014).
2 Lonigan et al. (Citation2008) did not find any statistically significant difference between teacher- and parent-based interventions, while Marulis and Neuman (Citation2010) reported that the former are substantially more effective.
3 A common limitation of experimental designs refers to spill-over effects. The RCTs under examination use individual randomisation designs based on small samples. Hence, this bias should be of minor entity.
4 The second and third author of this article coded the data; the first author defined the coding instructions and intervened in an instance of disagreement on the inclusion of a study and in another instance concerning the interpretation of the experimental effects reported in an article. The analyses were carried out exclusively by the fourth author.
5 Not all studies reported the year when the study was carried out, but when they do, the publication year is sufficiently close to represent an acceptable approximation.
6 The criteria to identify deprived neighbourhoods (or families) vary across studies. The most common ones are family income and parental education.
7 In several SBR interventions, parents and/or children must have some familiarity with the native language to be eligible.
8 We did not pre-register the statistical design of the meta-analysis. The selection of the above-listed characteristics for heterogeneity analyses was based on the findings of previous research and on the constraints of data availability.
9 We used the routine “metan” of Stata for these statistical analyses.
10 Indeed, the mean effect size for other intervention methodologies targeting low-socioeconomic groups is even smaller (0.045, not reported).
11 This meta-analysis could not systematically assess the impact of other SBR methodologies that are widely adopted internationally, such as “Bookstart” and “Reach out and Read”. The former is a home visiting programme. The only RCT that evaluated this programme assessed only its impact on SBR frequency, reporting a null effect (O’Hare & Connolly, Citation2010). The latter is a paediatric visiting programme for which we could identify only one eligible study, which reported consistently positive impacts on reading practices but less systematic patterns for the impacts on children's skills (Golova et al., Citation1999).