Machine Learning System Design Interview, issue 14, Dec 1, 2025
The Gallbladder Illusion
Senior Machine Learning Engineer interview at Google for Health, and the interviewer asks:
“Our research team just handed you a gallbladder segmentation model with 99.2% test set accuracy. Is it ready for production?”
Why a 99.2% medical-AI model nearly killed a patient - and how the Black Patch Protocol exposes false understanding.
The full answer, with the mechanism and the arithmetic, is for paid subscribers on Substack.