The reliability or reproducibility of a measurement is it's

True value.

Explanation:

Hello,

We refer to reliability just when we take several measurements on the same subjects in order to verify the homogeneity, agreement and resemblance among the measurements. Poor reliability dwindles the accuracy of a single measurement and consequently lowers the confidence to track further changes in future measurements. In such a way, the reliability or reproducibility refers to the true value, more specifically in statistics.

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Reliability in statistics and psychometrics is the overall consistency of a measure. A measure is said to have a high reliability if it produces similar results under consistent conditions ... Scores that are highly reliable are accurate, reproducible, and consistent from one testing occasion to another.