Part of Yale's online series Understanding Medical Research: Your Facebook Friend is Wrong, this short lecture uses the image of an onion to explain how statistical findings in medical studies are built up in layers, each one adding assumptions and potential sources of error. The instructor walks through how a single headline claim rests on data collection choices, statistical tests, and interpretive leaps, and shows why peeling back each layer can change how much weight a result deserves. The talk is aimed at a general audience trying to judge health claims shared online, using plain language rather than technical notation, with the goal of making viewers more skeptical readers of medical news rather than turning them into statisticians.