| Accuracy | The closeness of agreement between a measured value and the true value of the measurand. |
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| Calibration | The process of comparing an instrument or measurement system against a known standard to determine its accuracy. |
| Measurement Uncertainty | A parameter associated with the result of a measurement that characterizes the dispersion of values that could reasonably be attributed to the measurand. |
| Reference Standard | A measurement standard of known accuracy used as a basis for calibration of other instruments. |
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| Traceability | The property of a measurement result whereby it can be related to a reference through a documented unbroken chain of calibrations. |
| Tolerance | The permissible limit of variation in a measurement, usually specified by standards or customer requirements. |
| Metrological Traceability | The ability to relate individual measurement results back to national or international standards, ensuring reliability of calibration. |
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| Uncertainty Budget | A detailed accounting of all known sources of uncertainty in a measurement process. |
| Set-up / Procedure | The defined method or configuration used to perform calibration or measurement accurately. |