This month the Bay Area Open Science Group is learning about Open Peer Review. Open peer review is the least practiced aspect of open science. Yet it may teach us a lot about how manuscripts can change from their submitted version to their (peer-reviewed) published version of record. Mario Malički from Stanford will give an overview of 21 studies that analyzed manuscript changes and their own study in which they analyzed changes between 121 epidemiology preprints and their subsequent published versions. Finally, Mario will present a call for declaring changes to manuscripts with each published paper.