Garbage in, garbage out. Estimates done with unreliable and fuzzy information are unreliable and fuzzy. In the UP it is understood that estimates done during inception are not dependable (this is true of all methods, but the UP acknowledges it). Early inception estimates merely provide guidance if the project is worthy of some real investigation in elaboration, to generate a good estimate. After the first elaboration iteration there is some realistic information to produce a rough estimate. After the second iteration, the estimate starts to develop credibility (see Figure 40.4).
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Useful estimates require investment in some elaboration iterations. |
This is not to imply that it is impossible or worthless to attempt early, accurate estimates. If possible, very good. However, most organizations do not find this to be the case, for reasons that include continuous introduction of new technologies, novel applications, and many other complications. Thus, the UP advocates some realistic work in elaboration before generating estimates used for project planning and budgeting.
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