Accuracy
Umbrella concept of trueness and precision — how close a measurement gets to the true value overall.
Also known as: measurement accuracy, overall accuracy
Accuracy per ISO 5725 combines two independent properties: trueness (closeness to the reference value, no systematic bias) and precision (small spread among measurements). A measurement system is accurate only when both conditions are met.
- True and precise → accurate (target: hits tight and centred)
- True but imprecise → correct on average, useless individually
- Precise but untrue → reproducibly wrong (calibration issue)
- Neither true nor precise → not accurate
In measurement system analysis, MSA Type 1 checks both aspects on a reference part (Cg for precision, Cgk additionally for trueness); MSA Type 2 (Gage R&R) further decomposes precision into repeatability and reproducibility.
See also
Used in
In the Algorithm Lab
Sources
- DIN ISO 5725-1: Genauigkeit (Richtigkeit und Präzision) von Messverfahren und Messergebnissen — Teil 1: Allgemeine Grundlagen und Begriffe
- VDA Band 5 — Prüfprozesseignung: Eignung von Messsystemen, Mess- und Prüfprozessen, 3. Auflage
- DIN 1319-1: Grundlagen der Messtechnik — Teil 1: Grundbegriffe