I may be wrong but this sounds like a confusion of accuracy vs. precision (http://en.wikipedia.org/wiki/Accuracy_and_precision http://en.wikipedia.org/wiki/Accu

I may be wrong but this sounds like a confusion of accuracy vs. precision (http://en.wikipedia.org/wiki/Accuracy_and_precision http://en.wikipedia.org/wiki/Accuracy_and_precision) edit: By which I mean that this clock could be precise to 10^-16 but be off by 10^-14 due to a mis-calibration.