Similar to all processes, the measurement system is impacted by both random and systematic sources of variation. These sources of variation are due to common and special causes. In order to control the measurement system variation
1) Identify the potential sources of variation.
2) Eliminate (whenever possible) or monitor these sources of variation.
Although the specific causes will depend on the situation, some typical sources of variation can be identified. There are various methods of presenting and categorizing these sources of variation such as cause effect diagrams, fault tree diagrams, etc., but the guidelines presented here will focus on the major elements of a measuring system.
The acronym S.W.I.P.E. is used to represent the six essential elements of a generalized measuring system to assure attainment of required objectives. S.W.I.P.E. stands for Standard, Workpiece, Instrument, Person and Procedure, and Environment. This may be thought of as an error model for a complete measurement system.
Factors affecting those six areas need to be understood so they can be controlled or eliminated.
Figure below displays a cause and effect diagram showing some of the potential sources of variation. Since the actual sources of variation affecting a specific measurement system will be unique to that system, this figure is presented as a thought starter for developing a measurement system’s sources of variation.
source : Analysis of measurement systems
