Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Funnel plots of study‐level short‐term effect sizes (upper left corner), follow‐up effect sizes (upper right corner), peer‐assisted instruction effect sizes (lower left corner), and small‐group instruction effect sizes (lower right corner)
