Table 1 Definitions of terms often used with regard to immunization data

Trueness (also “accuracy” and “unbiasedness”)

Closeness of a measurement or estimate to the exact or true value of the thing that was intended to be measured; (N.B.: ISO definition further specifies accuracy being combination of both “trueness” and precision)

[17, 23,24,25]

Concurrence (or “congruence”)

Degree of agreement between different methods intended to measure the same thing

Precision

Degree of spread of a series of observations or measurements - combination of repeatability and reproducibility; how tightly the distribution of an estimator clusters about its center; degree of being free of random error

[17, 24, 26]

Reliability (or “consistency”)

Repeated estimates/measurements produce similar results under similar conditions; the closeness of the initial estimated value(s) to the subsequent estimated values

[17, 24]

Repeatability

Degree of agreement (variation) of a measurement under constant conditions using the same instrument with the same operator over a relatively short period of time

[17]

Reproducibility

Degree of agreement (variation) of a measurement under non-standardized conditions, i.e., same measurement method but conducted by different operators over longer periods of time.

[17, 23]

Usability

Degree to which data are of sufficient quality (accuracy), completeness, timeliness to allow for effective decision making

Utilization (or “Use”)

Degree to which data are actually used in decision-making

Validity

Degree to which an assessment measures what it is intended to measure; degree of being free of systematic error

[17, 24, 27]