Which combination best describes measurements that are both correct and consistently close to each other?

• A. Not accurate, precise
• B. Not accurate, not precise
• C. Accurate, not precise
• D. Accurate, precise

Answer: (D)

Accuracy and precision describe how good measurements are. Accuracy means measurements are close to the true value. Precision means the measurements are close to each other. When measurements are both accurate and precise, they cluster tightly around the true value, giving reliable results. That is why the best description is accurate and precise. If measurements are not accurate but precise, they’re tightly grouped but around the wrong value. If they’re accurate but not precise, they’re near the true value on average but vary a lot. If neither, they’re far from the true value and scattered.