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Measurement FundamentalsMeasurement Errors

What are Measurement Errors?

At some point, differences in measurement results (measured values) will arise due to some factor. These differences are referred to as measurement errors. Measurement errors can be caused by a variety of factors, and countermeasures will need to be taken accordingly. When a measurement error occurs, it is important to examine the cause of the measurement error thoroughly before implementing any countermeasure. This is important for ensuring stable product quality.

Measurement Error Causes

Measurement errors can be broken up into three general categories.

Type of error Cause of error
Errors caused by the measurement system
  • Measurement errors originating in the measurement system
  • Deterioration of measurement accuracy over time (deterioration caused by wear in consumable components)
Errors caused by the user
  • Mishandling of the measurement system
  • Different degrees of skill of the users
  • User-specific methods of reading the scale
Errors caused by environmental conditions
  • Deformation of the measurement target caused by changes in temperature
  • Measuring in locations with varying brightness levels

Errors caused by the measurement system or environmental conditions can be eliminated by confirming the cause and implementing the appropriate countermeasures. Errors caused by the user may call for medium- to long-term countermeasures such as reevaluation of the measurement process and employee training.

Eliminating Measurement Errors

Measurement errors can be eliminated for objects that will be measured multiple times. However, it is unrealistic to think that countermeasures can be implemented in the inspection process. To obtain higher accuracy for any given measurement, it is necessary to implement countermeasures according to the cause of the Measurement error.

Solution Details
Eliminating intrinsic measurement system errors
  • Regular calibration
  • Regular maintenance and replacement of consumable components
  • Accuracy confirmation before starting work and after completion
Change judgement criteria Narrow the tolerance range for a stricter acceptable judgement range
Create a system that can compensate for individual differences
  • Standardise the measurement method (measurement process)
  • Implement training aimed at improving the skill of workers
  • Adopt automatic measurement systems in order to eliminate human errors
  • Replace contact-type measurement systems with non-contact-type measurement systems
  • Switch to inline measurement for targets requiring measurement at multiple locations

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