> relatively fixed errors can be calibrated out

That's what I was pondering. If you know that the result is in error
by a known amount in known circumstances then you can apply a
known fix. For measuring a battery to 0.1V or temperature to 0.5C
some roughness in the method may be tolerable. That's not forgetting
that the A/D has a guaranteed accuracy available if that's what's really
needed

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