Effect Size Estimation in Neuroimaging

A central goal of translational neuroimaging is to establish robust links between brain measures and clinical outcomes. Success hinges on the development of brain biomarkers with large effect sizes. With large enough effects, a measure may be diagnostic of outcomes at the individual patient level. Surprisingly, however, standard brain-mapping analyses are not designed to estimate or optimize the effect sizes of brain-outcome relationships, and estimates are often biased. Here, we review these issues and how to estimate effect sizes in neuroimaging research.