Layperson’s Definition:

An analysis performed by a Party to quantitatively assess the quality of their inventory. In practice, developing uncertainty estimates is both difficult and often subjective. As a reviewer, the work performed by the Party in developing its uncertainty analysis is useful information for assessing improvements made or to be made by the Party to its inventory.

IPCC Definition:

A general and imprecise term which refers to the lack of certainty (in inventory components) resulting from any causal factor such as unidentified sources and sinks, lack of transparency etc.

Statistical Definition:

An uncertainty is a parameter, associated with the result of measurement that characterizes the dispersion of the values that could be reasonably attributed to the measured quantity. (e.g., the sample variance or coefficient of variation). An uncertainty analysis of a model aims to provide quantitative measures of the uncertainty of output values caused by uncertainties in the model itself and in its input values, and to examine the relative importance of these factors.