What is the term for the closeness of agreement between a measurement result and an accepted reference value?

The term that describes the closeness of agreement between a measurement result and an accepted reference value is accuracy. Accuracy indicates how close a measured value is to the true value or the standard accepted value. In contexts like radon measurement, achieving high accuracy is essential for ensuring that the results reflect true radon levels, which is critical for health assessments and remediation decisions.

In contrast, precision refers to the consistency of repeated measurements, not necessarily their closeness to a true value. Bias refers to systematic errors that could cause measurements to deviate from the true value, but it does not directly assess agreement with the reference value. Reliability relates to the consistency of a measurement over time or across different situations, but it is not a direct measure of the closeness to a reference. Understanding these distinctions underscores why accuracy is the correct term for this particular context.