An Introduction to the Grade of Confidence Used to Characterize Uncer- tainty Around the WHO and UNICEF Estimates of National Immuniza- tion Coverage

Uncertainty is a complex phenomenon and is nearly ubiquitous, at least in real-world settings [2]. Depending on the domain in which one works, the definition of ‘uncertainty’ may differ slightly. We consider uncertainty to be a state of limited or imperfect knowledge about a measurement, event or outcome. This uncertainty may derive from incomplete data, contextual factors that indirectly influence or perhaps conflict with existing information as well as from other known and perhaps unknown sources [3]. It is important to note, however, that uncertainty does not necessarily imply that an inference or judgement is incorrect [4].