It will be interesting to see, but they ran that study for year and a half or more (listed in article) collecting data based on the old watch is probably to try to see how well they could detect afib just from the heart rate sensor.

Apple is a big rich company, but I imagine their lawyers wanted to make sure they were REALLY sure they weren’t about to screw themselves over with tens of thousands of lawsuits, above and beyond the FDA requirements.

I think the ratio of true to false positives is vastly more interesting and an indicator for how well the technology is performing and if the burden is reasonable or not.