Published studies of intervention effects probably report effect sizes that are larger than the true effect size. There are probably many reasons for this, but one can be thought of as a "winner's curse." In this essay, I discuss evidence from two recent studies that highlight how evidence clearinghouses might inadvertently expose…

The What Works Clearinghouse (WWC) serves as a central and trusted source of scientific evidence for what works in education. The WWC designs its resources to help educators, administrators, families, researchers, and policymakers make evidence-based decisions. In fall 2023, the WWC convened the Small Working Group of Experienced Education…

Clearinghouses set standards of scientific quality to vet existing research to determine how "evidence-based" an intervention is. This paper examines 12 educational clearinghouses to describe their effectiveness criteria, to estimate how consistently[underlined] they rate the same program, and to probe why their judgments differ. All the…