Accuracy and Precision

How can you tell that a measurement is accurate or precise?

Accuracy and precision are common terms in measurement. Incorrect usage of these terms usually occurs to beginners since both are related to measurement.

The figure shown below is a dartboard. Assume that the bull’s-eye is the actual value and the hit marks are the measured values.

Low Accuracy, Low Precision

The hit marks are far from the bull’s-eye and far from each other.

Low Accuracy, High Precision

The hit marks are far from the bull’s-eye but close to each other.

High Accuracy, Low Precision

The hit marks are near the bull’s-eye but far from each other.

High Accuracy, High Precision

The hit marks are near the bull’s-eye and close to each other.