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…

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…