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

From: Defining & assessing the quality, usability, and utilization of immunization data

Term Definition References
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]