In analytical measurements, which term describes the closeness of the result to the true value?

• A. Precision
• B. Mean
• C. Error
• D. Accuracy

Answer: (D)

Accuracy describes how close a measurement is to the true value. In analytical measurements, you want results that agree with the actual quantity, reflecting proper calibration and low systematic error. Precision, by contrast, is about repeatability—how close repeated measurements are to one another, regardless of how close they are to the true value. You can have measurements that are highly precise but biased (close to each other but not near the true value), or accurate on average but not highly precise (close to the true value on average with more scatter). The mean is just the average of measurements, and error is the difference between a measurement and the true value. Therefore, the term describing the closeness to the true value is accuracy.