Instrumentation · on the desk since 2026-02
Callum Reith
Reference hardware — sleep, heart rate, step counting
Six years as a biomedical instrumentation technician in a hospital sleep unit, where the job was mostly making sure the reference channel was the thing you could trust when the patient record and the trace disagreed.
Builds the desk's comparison rigs and owns the calibration schedule. If a figure on this site came off a sensor, he is the person who checked the sensor first.
Conflicts
No affiliate accounts, no consultancy, no equipment accepted from any wearable or sensor manufacturer. Buys every device under test at retail.
Conflicts statements are updated with a date rather than rewritten. Roster last changed 2026-08-10.
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Published here
7 items
Step counts from nine wear positions, worn simultaneously, against a mechanical hand tally
What has actually been measured about calorie-app accuracy, and by whom?
How accurate is wrist heart rate compared with an ECG chest strap?
How accurate is the body fat percentage on a smart scale?
How accurate are step counters? Phone, watch and pedometer against a hand tally
Which home blood pressure monitor is accurate, and does cuff size matter more than the device?
Which sleep tracker is most accurate, and can any of them measure sleep stages?