(PREPRINT) BrainEffeX: A Web App for Exploring fMRI Effect Sizes

Effect size estimation is crucial for power analyses and experimental design, but poses unique challenges in fMRI research due to the complexity of the data and analysis techniques. Here, we introduce an interactive web application for exploring fMRI effect maps (neuroprismlab.shinyapps.io/BrainEffeX). We utilized large fMRI datasets to obtain precise voxel-wise and multivariate effect size estimates from “typical” fMRI study designs: brain-behavior correlation, task vs. rest, and between-group analyses of functional connectivity and task-based activation maps. The app is intentionally designed as a growing resource, and we welcome contributions of large (n > 500) datasets.