Duration of a project's

terminal element In category theory, a branch of mathematics, an initial object of a category is an object in such that for every object in , there exists precisely one morphism . The dual notion is that of a terminal object (also called terminal element): ...

is the number of calendar periods it takes from the time the execution of element starts to the moment it is completed. Duration should not be confused with work. E.g. it takes three days for a

snail-mail The mail or post is a system for physically transporting postcards, letters, and parcels. A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal syst ...

letter to arrive at point B from point A, whereas the work put into mailing it may be 0.5 hours. Strictly speaking, the phrase ''Duration of terminal element X is 5 days'' is incomplete. It fails to specify the following: * the

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking, ...

with which the completion is expected in the time allotted (since any estimate is only a prediction about the uncertain future, see

critical chain Critical chain project management (CCPM) is a method of planning and managing projects that emphasizes the resources (people, equipment, physical space) required to execute project tasks. It was developed by Eliyahu M. Goldratt. It differs from ...

) * the resources to be used (sometimes using more resources or different resources speeds things up) * the assumptions which were made * the author of the estimation * the date the estimate was made * the work schedule of the resources * etc. So the improved statement could read: :''I, Marek Kowalczyk, as of 27 March 2005 strongly believe that if I fully applied myself to competing terminal element X and worked 8 hours a day every day, including holidays, and had all the materials at hand, then I would have completed it in 5 calendar days. See metamodeling. It may seem unwieldy to use such complicated statements, but lack of detail often leads to misunderstanding.

See also