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DETERMINING MEASUREMENT ACCURACY

by Hristo Stefanov

Start ý Defining the Terms ý A Little Theory ý Sources of Error ý Error Budget ý Error Budget Example ý Offset and Gain Errors ý Sources and PDF

DEFINING THE TERMS

Iýd like to review some definitions that I will be using in this article. That way youýll receive a better understanding of the content.

Accuracy of measurement is the closeness of the agreement between the result of a measurement and a true value of the measured value. Note that accuracy is a qualitative concept, and the term "precision" should not be substituted for "accuracy."

Error is the difference between a computed, estimated, or measured value and the true, specified, or theoretically correct value. It can also be described as a deviation from a correct value caused by a malfunction in a system or a functional unit.

Random error is the result of a measurement minus the mean that would result from an infinite number of measurements of the same measured value carried out under repeatable conditions. Note that random error is equal to error minus systematic error, and because only a finite number of measurements can be made, itýs possible to determine only an estimate of random error.

And finally, systematic error is the mean that would result from an infinite number of measurements of the same measured value carried out under repeatable conditions minus the true value of the measured value. Note that systematic error is equal to error minus random error, and like true value, systematic error and its causes cannot be completely known.

Hereafter, I will talk about only systematic errors because random errors are difficult to assess.

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