My [device] reports [a metric].
How is that measurement derived,
where is it reliable, where is it an
estimate, and what can it definitely
not tell me?

How Much to Trust a Wearable

Where the number is measured and where it's inferred.

Prompt

My [device] reports [a metric] and I'm not sure how seriously to take it. Explain how that measurement is actually derived, where it's reliable, where it's an estimate, and what it definitely cannot tell me.