Metrology and the mechanical engineer

The purpose of a measurement system or procedure is to quantify a stochastic variables in a meaningful manner. Metrology, the science of measurement, ensures that the value of a stochastic variable can be expressed as a multiple or a submultiple of the applicable international unit of measure. Measured values should be unbiased and precise within acceptable and affordable limits. Measuring variables on-line is an effective methodology to interrogate dynamic stochastic systems. Probability and statistics provide powerful tools and techniques to test for bias and to estimate precision. The mechanical engineer stands to benefit of some basic knowledge of statistics as it applies to measurements with on-stream analysers. The purpose of this paper is to arouse more than a passing interest in metrology.