The Every Student Succeeds Act (ESSA) introduced a framework for evaluating the effectiveness of educational programs, practices, and interventions. This framework is known as the ESSA tiers of evidence, and it categorizes evidence into four levels, guiding educators and policymakers in making informed decisions to improve student outcomes. Understanding these tiers is crucial for schools and districts to choose interventions with a proven success track record.
The pinnacle of the evidence tiers, Tier 1, is reserved for interventions supported by one or more well-designed and well-implemented randomized control trials (RCTs). This means the intervention has been rigorously tested and demonstrated a statistically significant effect on improving student outcomes. Interventions that reach this tier provide the strongest assurance of effectiveness.
Tier 2 requires interventions to have evidence from well-designed and well-implemented quasi-experimental designs (QEDs). These are studies that, while not randomized, still provide a reliable measure of an intervention's effectiveness. To be considered moderate evidence, these studies must demonstrate a statistically significant effect on improving student outcomes.
This tier includes interventions with evidence from well-designed and well-implemented correlational studies with statistical controls for selection bias. In other words, these interventions show a positive effect on student outcomes. Still, the evidence is not as strong as Tiers 1 or 2 because it is not from an experiment or quasi-experiment.
Tier 4 is for interventions supported by a rationale based on high-quality research findings or positive evaluation that such interventions will likely improve student outcomes. However, these interventions might not yet have the empirical evidence that meets the requirements of the higher tiers.