Good ol fashioned machine learning, not AI like today’s buzzword for LLMs
Apple used AI to sort through the data from 100,000 people enrolled in a heart and movement study it originally launched in 2019 to see whether it could find features in the signal data from the watch's main heart-related sensor that it could then match up with traditional blood pressure measurements, Desai said.
After multiple layers of machine learning, Apple came up with an algorithm that it then validated with a specific study of 2,000 participants.