YOKOGAWA WT310EH - Page 131

App-25
IM WT310E-01EN
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Index
Note
Accuracy and Precision
Measurement accuracy refers to how close a measurement is to the true value. In other words, it indicates
the deviation of a measured value from the true value. Measurement precision refers to how close
measurements of the same quantity are to each other.
Forexample,letusconsiderthemeasuredresultsoftwovoltmeterswhen1.00Vismeasuredthreetimes.
  VoltmeterA VoltmeterB
1stmeasurement 1.02V  1.04V
2ndmeasurement 1.00V  1.05V
3rdmeasurement 0.98V  1.06V
VoltmeterAmeasurementsareclosertothetruevalue(1.00V).SowecansaythatvoltmeterAismore
accuratethanvoltmeterB.
Ontheotherhand,thethreevoltmeterBmeasurementsareclosertoeachotherthanthoseofvoltmeterA.
SowecansaythatvoltmeterBismoreprecisethanvoltmeterA.
Measurement Error
A measurement error is the difference between the actual measurement and the true value.
Appendix 5 Measurement Accuracy and Measurement Error