[zmgsabst]

You can’t derive the correct value if all your measurements are (eg) +1ns due to inaccurate path length in your model.

Your collection of measurements will converge, just as if you had built the device you intended to — but they’ll converge to the wrong value, because you’re measuring the time incorrectly every measurement, and so averaging that out doesn’t do anything.

Your test is precise but inaccurate.

The whole context of this is about a specific instrument measuring electron properties — or in my example, timing neutrino flights. So… yes, we’re talking about precision and accuracy.

[jvanderbot]

You're explaining accuracy vs precision, which I get.

The answer actually was: Yes, there's only one instrument. So yes, you can't average out systemic biases. So yes, I guess you can say something about

"We measure eccentricity zero with 1 part in 1E+17, which is really precise, but you'll just have to trust us it's also accurate."

Anyway, we know what everyone meant.