Repeatability is the short-term, within-system spread of a measurement, often called equipment variation (EV). It captures gauge noise, fixturing play and small positioning differences, estimated from repeated readings of one part with nothing else changed. Poor repeatability points at the instrument itself: worn contacts, vibration, electrical noise, unstable focus or a part that does not seat the same way twice.
Repeatability is fine, the tool reads within 0.2 nm on back-to-back loads. The problem is between the two tools.
Also heard as
- equipment variation
- EV
- test-retest
Do not mix it up with
- Reproducibility: Reproducibility is the variation added when operators, tools or setups change; repeatability holds all of those fixed.
Related terms
Reproducibility
Variation in measurement results when different operators, gauges or setups measure the same items.
Gauge R&R
Study that measures how much observed variation comes from the measurement system's repeatability and reproducibility.
Replicate
Independent rerun of the same factor settings from scratch, which gives a true estimate of experimental error.
MSA
Measurement systems analysis: the set of studies that prove a gauge is fit for the decisions its data will drive.