How does accuracy differ from precision?

• A. Accuracy refers to closeness to target; precision refers to repeatability
• B. Accuracy refers to closeness to target; precision refers to how close repeated measurements are to the target
• C. Accuracy refers to how close a measurement can be to the target value and precision refers to how close repeated measurements are to one another
• D. Accuracy and precision are interchangeable

Answer: (C)

The important idea here is distinguishing what accuracy measures from what precision measures. Accuracy is about how close a result is to the true value you’re aiming for. Precision is about how repeatable your measurements are—how tightly they cluster when you repeat the measurement.

The statement that does best at capturing this says that accuracy is about closeness to the target value, and precision is about how close repeated measurements are to one another. That framing is precise and aligns with how these terms are used in practice. For example, if you measure a 100 g standard several times and get 99.8 g, 100.1 g, and 99.9 g, the average is very close to the true value (good accuracy) and the results are close to each other (good precision). If all the measurements cluster around 99.8 g, you have high precision but low accuracy. If measurements are spread out but average near 100 g, you have good accuracy but low precision.

So, accuracy = closeness to the true value; precision = repeatability or consistency of measurements.