How is precision defined?

• A. Closeness to true value
• B. Reproducibility of repeated measurements
• C. Calibration of instrument
• D. Readings at different times

Answer: (B)

Precision is about how reproducible or consistent repeated measurements are when you repeat the measurement under the same conditions. It shows how tightly the results cluster together, regardless of whether they hit the true value. In practice, precision is assessed by the spread of repeated measurements; a small spread means high precision.

Closeness to the true value describes accuracy, not precision. Calibration relates to accuracy by ensuring the instrument reads correctly, while readings at different times can reflect drift or changes and don’t define precision. Therefore, reproducibility of repeated measurements best captures the concept of precision.