Measurement System Analysis (MSA) deals with the Study of Measurement accuracy. It helps in getting a right and confident decision, especially if the decision is based on the measured values. When we are taking a decision based on a measured value, We must be sure that the measurement taken is dependable.It is also referred as Gauge R&R (Gauge Repeatability and Reproducibility)
It is the Quantitative assessment of how much variation (repeatability and reproducibility) is in a measurement system compared to the total variation of the process or system.
Measurement – The act of obtaining knowledge about an event or characteristic through measured quantification or assignment to categories.
Measurement Accuracy – For a repeated measurement, it is a comparison of the average of the measurements compare to some known standard.
Measurement Precision – For a repeated measurement, it is the amount of variation that exists in the measured values.
Measurement Systems Analysis (MSA) – An assessment of the accuracy and precision of a method of obtaining measurements.
A Measurement System shall be meeting all the following requirements within limits for that to be considered as a dependable measurement system.
Accuracy – It should produce a number that is “close” to the actual property being measured, that is, it should be accurate
Repeatability – If the measurement system is applied repeatedly to the same object, the measurements produced should be close to one another, that is, it should be repeatable. It is the extent to which repeated measurements of a particular object with a particular instrument produce the same value.
Linearity – the measurement system should be able to produce accurate and consistent results over the entire range of concern, that is, it should be linear
Reproducibility – The extent to which repeated measurements of a particular object with a particular individual produce the same value. A measurement system should produce the same results when used by any Operator, the results should be reproducible.
Stability – When applied to the same items the measurement system should produce the same results in the future as it did in the past, that is, it should be stable
In addition to the above, We need to look at other important aspects like
Bias – The difference between the average measured value and a reference value is referred to as bias.
Resolution – Ability of the measurement system to divide measurements into required denomination i.e the decimal point to which a system can measure.
Measurement System Analysis consists of Calibration and Maintenance of the Measurement System and also statistical Studies. The Measurement System Analysis will help us to decide if the measurement system can be Used or not.