A recent meta-analysis published in the Review of Educational Research intends to identify and understand the intervention characteristics associated with the largest reading effect sizes.

To support students’ reading outcomes, current models of intervention delivery have utilized multi-tiered systems of support (MTSS), also referred to as Response to Intervention (RtI). Within current MTSS and RtI frameworks, intervention levels are organized around three tiers.

• Tier 1 consists of delivering general education classroom instruction.
• Tier 2 consists of small group or 1:1 tutoring.
• Tier 3 consists of 1:1 instruction, with higher dosage and personalization.

However, despite the promise of early reading interventions, about 18% to 55% of K–3 students with reading disabilities (SWRD) under Tier 2 intervention have continued to struggle in reading. Therefore, it remains critical to better understand how and when to intensify reading interventions.

Since linear models in intervention research and meta-analyses have been unable to substantiate the claim that a larger dosage (i.e., more hours of intervention) produces significantly larger effect sizes than interventions with less dosage (i.e., fewer hours of intervention) and based on the observed nonlinear association between reading instruction (i.e., hours of instruction) and reading outcomes for Grade K-3 students with reading difficulties (K-3 SWRD), the authors conducted a nonlinear meta-analysis to investigate the effect sizes through modelling the maximum effect and optimal dosage to respond to the following research questions:

1. what is the optimal dosage and maximum predicted effect size from reading interventions for K–3 SWRD?
2. when investigating outcome type, intervention components, group size, or norm-referenced moderators, to what extent did the optimal dosage and maximum predicted effect size vary from the overall optimal dosage and maximum predicted effect size presented in the first research question?

Results suggest that reading intervention effect sizes, relative to a comparison condition, increase until approximately 40 hours of small group K–3 SWRD reading instruction. After this point, effect sizes tend to decline. For students who have inadequately responded to small group reading instruction, we also identified 1:1 grouping as a possible method to increase student outcomes after the 40-hour time point is reached.

Source: Roberts, G. J., Dumas, D. G., McNeish, D., & Coté, B. (2021). Understanding the Dynamics of Dosage Response: A Nonlinear Meta-Analysis of Recent Reading Interventions. Review of Educational Research. https://doi.org/10.3102/00346543211051423