Unknown unknown
In decision analysis, an unknown unknown, often shortened to unk-unk, is an uncertainty that is unanticipated and, hence, unaccounted for in a formal decision model. Unk-unk may also refer to unanticipated decision variables, although this usage is less common. U.S. Secretary of Defense Donald Rumsfeld won the 2003 Foot in Mouth Award from the Plain English Campaign for the following helpful definitions given at the Defense Department Briefing on February 12, 2002: - "Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns — the ones we don't know we don't know."
External links- Transcript of Defense Department Briefing, February 12, 2002
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