Uncertainty

Every Measurement Includes Error...  

It's the nature of the "beast",  you cannot escape it, but you can understand it and use the error to better understand the measurement process and the results of measurements.

Most metrologists* understand these details. In fact, they study them and provide better understanding for the poor engineer, scientist or technocrat who has to deal with the application of any measurement device in an attempt to measure a variable or property of an object.

Most National Measurement Institutes (NMIs) like NIST in the U.S.A. or the NPL in the U.K. or any of the member organizations of the International community of metrology organitiona listed on the International Bureau of Weights & Measures (BIPM) website.

Here are a few quotes and links from NIST's webpage on measurement uncertainty:

The GUM defines measurement uncertainty as a "parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand''.

The VIM defines it as a "non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used''.

References

• Barry N. Taylor and Chris E. Kuyatt (1994). Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results. NIST Technical Note 1297.
• Evaluation of measurement data – Guide to the expression of uncertainty in measurement JCGM 100:2008 (GUM 1995 with minor corrections)
• Evaluation of measurement data – Supplement 1 to the "Guide to the expression of uncertainty in measurement" – Propagation of distributions using a Monte Carlo method JCGM 101:2008

Another resource for the not-so-timid, aspiring metrologist is:

The NIST Uncertainty Machine, a Web-based software application to evaluate the measurement uncertainty associated with an output quantity defined by a measurement model of the form y = f(x0,...,xn).

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* Metrologist: One who practices metrology, Metrology: The science of weights and measures.