Accuracy and precision - Wikipedia
https://en.wikipedia.org/wiki/Accuracy_and_precisionIn a set of measurements, accuracy is closeness of the measurements to a specific value, while precision is the closeness of the measurements to each other. Accuracy has two definitions: 1. More commonly, it is a description of systematic errors, a measure of statistical bias; low accuracy causes a difference between a result and a "true" value. ISO calls this trueness.