Likelihood is a colloquial expression of probability, often couched in broad bands of probability. The difficulty is that my likelihood, absent a clear definition of what I mean by the gradations I select, may be very different from your likelihood, and that a third individual may translate our individually different values as agreement with his value set, a third range not common to either of ours. For example, I might reasonably think that a 51% probability is very likely, you might believe in a 75% probability threshold, and our third observer, who thinks of very likely as 95% or more, is certain that we have agreed with him that the big one is about to happen, today, by 1600. Likelihood is also often described in terms that are subject to wide interpretation. For example, Secretary of Homeland Security Michael Chertoff stated that he had a gut feel that a major terrorist attack would be launched inside the United States in the Summer of 2007. Some viewed this as an almost certainty – after all, if anyone should know it would be the Secretary of Homeland Security. Others scratched their heads wondering how to quantify a gut feel as the basis for operational planning. And in the final analysis, no attack came.