Calibration of measuring instruments is important because it ensures that the instrument is __________.

• A. Precise
• B. Reliable
• C. Calibrated
• D. Accurate

Answer: (D)

Calibration targets aligning readings with a trusted standard so the results reflect the true value of what’s being measured. This is about accuracy—the closeness of a measurement to the actual quantity. When an instrument is calibrated, systematic bias is reduced, meaning the readings are kept in line with the true value rather than consistently off by a fixed amount. Strictly speaking, you can have a very precise instrument that yields the same value every time but that value might still be wrong if there’s a bias; calibration corrects that bias to improve accuracy.

Precision, by contrast, is about repeatability—getting the same result each time under the same conditions, which doesn’t guarantee that result is the true value. Reliability concerns consistent performance over time and under varying conditions, which is related but not the same as measuring accuracy. Calibrated describes the state after adjusting to standards, but the essential quality gained through calibration is accuracy.