Conditions of measurement

Many different factors may contribute to the variability between replicate measurements, including the operator; the equipment used; the calibration of the equipment; the environment; the time elapsed between measurements.

Two conditions of precision, termed repeatability and reproducibility conditions are useful for describing the variability of a measurement procedure. Other intermediate conditions between these two extreme conditions of precision are also conceivable and useful, such as conditions within a single laboratory.

• Reproducibility
  Reproducibility is a measure of precision under a defined set of conditions: different locations, operators, measuring systems, and replicate measurements on the same or similar objects.
• Intermediate precision
  Intermediate precision (also called within-laboratory or within-device) is a measure of precision under a defined set of conditions: same measurement procedure, same measuring system, same location, and replicate measurements on the same or similar objects over an extended period of time. It may include changes to other conditions such as new calibrations, operators, or reagent lots.
• Repeatability
  Repeatability (also called within-run precision) is a measure of precision under a defined set of conditions: same measurement procedure, same operators, same measuring system, same operating conditions and same location, and replicate measurements on the same or similar objects over a short period of time.