Sample Size Guide
Bill & Melinda Gates Foundation
The Sample Size Guide provides an overview of the sample size considerations for each of the evidence-building phases: Design the Solution (Phase 1), Refine the Solution (Phase 2), Assess for Early Evidence of Success (Phase 3), and Validate Effectiveness (Phase 4). Organizations can use this document to inform their study’s sample sizes as they begin recruitment and planning for measurement and evaluation activities. In Phase 3 (Assess for Early Evidence of Success) and Phase 4 (Validate Effectiveness), organizations can use this guidance as a starting point but should work with a research partner to determine the specific sample size needed for their study.
This guide is part of a suite of tools designed to support grantees as they develop, refine, and scale evidence-based solutions (programs, products, or practices) that demonstrate success in improving educational outcomes for students who are Black, Latino, and/or experiencing poverty and promote the adoption of evidence-based solutions more broadly.