A measurement system comprises the totality of all elements that directly or indirectly influence the determination of the value of the physical quantity to be measured. In detail, these are: the actual object to be measured, the measuring equipment or devices used, the person(s) measuring, the environment and the methods of measurement and evaluation applied. All these components together define a complete measurement process, which is often used synonymously with the term measurement system. Not only complex experimental apparatus is referred to as a measurement system; a single measuring device can also define a measurement system.
Measurement deviations within the measurement system and their possible causes
According to the DIN standard, deviations from the actual value of the measurement are no longer called measurement errors, but measurement deviations. This takes into account the fact that error-free measurements are ultimately not possible.
Possible causes for measurement inaccuracies can be:
In the case of measurement inaccuracies, a distinction is made between influenceable and non-influenceable errors (air turbulence, thermal noise, humidity). If the errors are constant and systematically caused, they are also referred to as offset; if they rise or fall during the course of measurement, the terms trend and drift have become established.
Because the elements of measurement systems correlate with each other as a system, errors in measurement can never be attributed monocausally to just one factor, but must always be interpreted in their interference with the totality of all elements of the measurement system.
Methods of compensation for measurement errors in measurement systems
In meteorology and quality management, a number of targeted methods for compensating measurement errors have become established. The most important measure here is the calibration, adjustment and calibration of measuring instruments to ensure the comparability of results.