Assessing observer variability: a user’s guide

Assessment of observer variability represents a part of Measurement Systems Analysis (1) and is a necessary task for any research that evaluates a new measurement method. It is also necessary to perform observer variability assessment even for well tested methods as a part of quality control. It is also a favorite topic to be raised by reviewers during a peer review, often as a veiled disguise for a lack of credence in truthfulness of the data reported