Wearable devices are most valuable when they measure metrics that vary non-intuitively day-to-day, can be measured accurately, and provide real-time, actionable feedback.

“My framework for what must be true of a “good” wearable (Attia Postulates): 1. What you’re measuring matters (e.g., HRV—matters vs. # steps taken—not so much). 2. What you’re measuring differs from day to day in ways that are not intuitive or linear (see above). 3. What you’re proposing to measure you can actually measure accurately (e.g., HR—can be measured accurately vs. subtle changes in body position—probably can’t be measured well enough yet). 4. You can report the data in a timeframe that is relevant to learn or act on (i.e., real-time info versus delayed info). 5. You can provide corrective, actionable feedback, if necessary. (This is huge and largely missing in most applications.)”