## What is the Variation in the Measurement System?

→ It is sometimes described as spread or dispersion to distinguish it from systematic trends or differences.
→ Measures of variation are either properties of a probability distribution or sample estimates of them.
→ The range of a sample is the difference between the largest and smallest value.
→ The observed variation in process output is not simply due to the process itself, but it is due to the process and gauge that results in an inadequate Measurement System.
→ It is mentioned in the below picture.

### Classification of Variation in Measurement System:

→ The classification is mentioned in the below picture.

[1] The actual process variation is due to the below parameter in the system
⇢ e.g. Cycle time
⇢ Dimension data
⇢ Number of defects
⇢ Some other factor

[2] The measurement system variation further divided into two parts
⇢ (A) Precision (related to variability): It is the closeness between the measured value, how close all value to each other
⇢ (B) Accuracy (related to a central location): It is the closeness between the true value and measured value.
⇢ (A) Precision is divided into 3 parts
(a) Resolution: It is the ability of the instrument with an operator to detect small changes in the characteristic of the object.
(b) Repeatability: It is due to the error in the gauge
(c) Reproducibility: It is due to the operator's error or we can say that the appraiser's error
with examples
⇢ (B) Accuracy is divided into 3 parts
(a) Linearity: It is the bias with respect to length
(b) Bias: It is the difference between the average measured value with true value.
(c) Stability: It is the bias with respect to time.

### Causes of Measurement Variation:

→ The purpose of the system is to validate before they are considered true data and used as a basis for decision-making.
→ Refer to some of the below important causes.

[1] People:
→ People are the most important factor in this.
→ Due to the repetitive activity of measurement, it becomes a monotonous task, and sometimes errors are made.
→ Also, sometimes employees intentionally avoid work due to some other reason and manipulate the readings.

[2] Equipment/Instrument:
→ Faulty equipment or instruments is another major factor that results in getting inaccurate readings.
→ The equipment or instrument is not calibrated then we can not rely on that. It is not recommended. → Due to continuous use instruments wear out.
→ Regular maintenance and calibration of the instrument are essential.

[3] Complex Calculation:
→ Sometimes, due to complex calculations, the possibility of error is due to a lack of proper communication or selection of a proper data set.

[4] Lack of Standard Operating Procedures (SOP):
→ It is important that the standard operating procedure should be available for any operation or measurement.
→ Also, it should be communicated to every person that needs to know it.