International Portal of Teacher Education

Source: Educational Researcher, 43(5), June/July 2014, p. 242-252.

In this article, the authors illustrate that populations and study samples can change over time.
They present data from 5 randomized control trials of the efficacy of Kindergarten Peer-Assisted Learning Strategies, a supplemental, peer-mediated reading program.
The studies were conducted across 9 years and involved 2,591 students.

Findings demonstrate a dramatic increase in the performance of control students over time.
The results suggest the need for a more nuanced understanding of the counterfactual model and its role in establishing evidence-based practices.