Glossary
Calibration Terms
Calibration and metrology terms: accuracy, repeatability, hysteresis, uncertainty, TUR, traceability, guard bands, as found and as left.
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All Calibration Terms
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FormulaAccuracyAccuracy is how close a measurement is to the true value; in specifications it is the maximum…FormulaAccuracy SpecificationAn accuracy specification states how an instrument maker defines its maximum error, such as %…TermAs Found and As LeftAs found and as left are the calibration readings taken before any adjustment (as found) and…TermCalibrationCalibration is the comparison of an instrument reading with a known reference standard,…TermCalibration CertificateA calibration certificate is a formal document reporting calibration results, the reference…FormulaCalibration CorrectionA calibration correction is the value added to an instrument reading to obtain the corrected…FormulaCalibration CurveA calibration curve is a fitted relationship between instrument reading and true value, used to…TermCalibration IntervalA calibration interval is the time between scheduled calibrations, set so the instrument is…
kCoverage FactorCoverage factor k multiplies the combined standard uncertainty to give an expanded uncertainty…FormulaDeadweight TesterA deadweight tester generates a precise pressure by placing known masses on a piston of known area.TermDecision RuleA decision rule defines how measurement uncertainty is taken into account when stating that an…TermDriftDrift is a slow change in an instrument reading over time when the input stays the same.FormulaFive Point CalibrationA five point calibration checks an instrument at 0, 25, 50, 75 and 100 % of range, usually…FormulaGuard BandA guard band tightens the acceptance limit inside the tolerance to allow for calibration…FormulaHysteresisHysteresis is the difference between readings at the same input when approached from below…TermISO/IEC 17025ISO/IEC 17025 is the international standard for the competence of testing and calibration…
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FormulaLinearityLinearity is how closely an instrument output follows a straight line between input and output;…FormulaLocal GravityLocal gravity is the acceleration due to gravity at a site; it varies with latitude and height…FormulaMeasurement UncertaintyMeasurement uncertainty is a quantified range around a result within which the true value is…TermPrecisionPrecision is how closely repeated measurements of the same quantity agree with each other,…TermReference StandardA reference standard is the highest accuracy standard at a site, used to calibrate working…FormulaRepeatabilityRepeatability is the closeness of successive readings of the same input under the same…TermReproducibilityReproducibility is the closeness of results for the same quantity when conditions change, such…TURTest Uncertainty RatioTest uncertainty ratio compares the tolerance of the instrument under test with the uncertainty…
TPETotal Probable ErrorTotal probable error combines independent error sources, such as reference accuracy,…TermTraceabilityTraceability links a measurement result to national standards through an unbroken chain of…FormulaType A and Type B UncertaintyType A and Type B uncertainty are the two ways of evaluating uncertainty: Type A from…FormulaZero and Span ErrorZero and span error describe an instrument whose reading is offset at the bottom of the range…
Frequently Asked Questions
What does the calibration glossary cover?
Calibration and metrology terms: accuracy, repeatability, hysteresis, uncertainty, TUR, traceability, guard bands, as found and as left.
Are the formulas checked?
Yes. Formulas follow the relevant standards such as ISO 5167, and every worked example is calculated and checked.
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