UNFCCC Definition:

Accuracy is a relative measure of the exactness of an emission or removal estimate. Estimates should be accurate in the sense that they are systematically neither over nor under true emissions or removals, as far as can be judged, and that uncertainties are reduced as far as practicable. Appropriate methodologies conforming to guidance on good practices should be used to promote accuracy in inventories.

In statistics, accuracy is a general term which describes the degree to which an estimate of a quantity is unaffected by bias due to systematic error. It should be distinguished from precision.

Examples: Party X has detailed statistical data on its aluminum industry since the 1950s, including information on production technologies. However, its inventory utilizes a default average PFC emission factor applied to the total aluminum production.

Because the technology being used in this country has not been modernized, when emissions are reproduced by the review team using technology specific emission factors, the estimate is shown to be significantly greater. Party X has failed to provide an accurate and unbiased estimate, given the data available.