Repeatability
Precision under the tightest conditions: same operator, same instrument, same part, short time.
Also known as: equipment variation, EV, within-system variation
Repeatability is the variation observed when the same person measures the same characteristic on the same part with the same instrument multiple times in a short time frame. It captures pure equipment variation — the random spread the measurement system itself brings, with operator, time, and part held constant.
In MSA Type 1, repeatability is checked on a single reference part and normalised against tolerance via Cg / Cgk. A low Cg (< 1.33) already reveals poor repeatability — running a subsequent Gage R&R then is not worthwhile.
- Causes: electronic noise, mechanical play, reading error, thermal drift over a series
- Excludes operator effect (that is reproducibility)
- Excludes part-to-part effect (that is part variation)
See also
Used in
In the Algorithm Lab
Sources
- DIN ISO 5725-2: Genauigkeit (Richtigkeit und Präzision) von Messverfahren und Messergebnissen — Teil 2: Grundlegende Methode zur Bestimmung der Wiederhol- und Vergleichpräzision
- AIAG — Measurement Systems Analysis Reference Manual, 4th Edition (MSA-4), Chapter 4
- VDA Band 5 — Prüfprozesseignung, 3. Auflage