Repeatability is the variation of outcomes of an experiment carried out in the same conditions, e.g. by the same operator, in the same laboratory.
For example, repeatability of measurements of precise mechanical scales is the variation of weight values reported for a given constant mass by the same person, in conditions with the same temperature and humidity.
For continuous outcome variables, repeatability may be quantified via such measures as "repeatability standard deviation " or "repeatability variance ".
Repeatability is often considered in conjunction with reproducibility ; there is even a common acronym for this pair - "R&R".