Researchers Struggle to Use Apple Watch in Studies Due to Sudden Algorithm Changes

Researchers are rethinking plans to use the Apple Watch in studies after finding inconsistencies in the data gathered by the device (via The Verge).

Inconsistencies in the Apple Watch's heart rate variability data are reportedly caused by Apple tweaking the device's algorithms, meaning that data from the same time period can change without warning. Associate professor of biostatistics at the Harvard T.H. Chan School of Public Health and developer of the Beiwe data platform, J.P. Onnela, told The Verge:

These algorithms are what we would call black boxes — they're not transparent. So it's impossible to know what's in them.

Research fellows at Brigham and Women's Hospital exported the heart rate data from Apple Watches for the same period of time, but several months apart. The data should have been identical, but since it is filtered through an algorithm prior to export it was drastically different.

Apple changes its algorithms regularly and without warning, so exporting the same data at different times may use different algorithms. Beyond heart rate variability, researchers looking into sleep tracking have experienced similar problems with changes to algorithms.

This mostly precludes commercial devices from being used by researchers, resulting in the need for devices specifically designed to collect data for scientific studies. While this is adequate for some studies, it heavily constrains research into the medical value of commercially available products for users. Some researchers say that Apple should publicize the changes it makes to algorithms or make the Apple Watch's raw data available.