Reference value

The known and correct measurement associated with each part. It serves as a master value for comparison during measurement system analysis. For example, you have a known weight of 0.025g that you use to calibrate your scales.

Reference values help you determine the bias and linearity of your measurement system. Bias examines the difference between the observed average measurement and a reference or master value. It answers the question: "How accurate is my gage when compared to a reference value?" Linearity examines how accurate your measurements are through the expected range of the measurements. It answers the question: "Does my gage have the same accuracy across all reference values?"

Reference values can be determined in many ways, depending on industry standards and company and customer expectations. Some of the bases for reference values are:

·    Average of repeated measurements from more accurate measuring equipment

·    Values endorsed by a professional group

·    Values agreed upon by the affected parties

·    Values defined by law