What term describes the degree of closeness of a measured quantity to its true value?

The term that describes the degree of closeness of a measured quantity to its true value is accuracy. In measurement and data collection, accuracy refers specifically to how close a measured value is to the actual (or "true") value of the quantity being measured. It is an essential concept in fields like radiological measurement, where understanding the true levels of radon is critical for assessing health risks.

Understanding accuracy helps professionals determine if their measurement techniques and instruments are effective and valid. A highly accurate measurement suggests that the methodology and equipment used convey reliable results.

In contrast, precision refers to the consistency of repeated measurements—how closely the values cluster together, without necessarily being close to the true value. Reliability speaks to the consistency of a measurement process over time, while validity relates to the extent to which a test accurately measures what it is supposed to measure. Thus, these terms, while related to the quality of measurements, emphasize different aspects of data collection and analysis.