Reference-device validation

Judge a wearable by correlating it against a trusted reference, not marketing claims: ECG chest strap (Polar H10) for exercise HR, EEG for sleep. Two honesty rules from the CIRQA reviews: state your reference's own accuracy tier (rob-ter-horst calls consumer EEG a "silver standard"), and refuse comparisons the reference can't support (dc-rainmaker won't grade sleep stages against a device that's only ~80% accurate: "we would never judge heart rate accuracy against a chest strap that was only accurate 80% of the time").

Sources: Quantified Scientist, DC Rainmaker