For decades now, the project management world has been divided between top-down estimation and bottom-up estimation. While a top-down approach might have limitations, it is perhaps the only way to get some meaningful estimates at the start of a project. A bottom-up approach might be a great way to get more accurate and reliable estimates but you might have to wait for a problem to be whittled down to a small level to get reliable estimates. Both are required for a comprehensive and useful project planning, but unfortunately, most people use one over the other, and the Agilists abandoning top-down in favor of the highly accurate but low-lookahead bottom-up methods.
Dec 27, 12