Painting the Missile with PERT vs Eating the Elephant.
Estimation is practical for determining if a project can go through, or if complexity should be reduced to make it feasible.
For estimating complex project schedules, two techniques were provided to better refine the modelling and accuracy of the times provided:
“Program Evaluation Review Technique (PERT)”, developed by the U.S. Navy to plan the Polar submarine project, provides a range of how long each task will take. With an “optimistic”, a “most likely” and and a “pessimistic” estimate, best and worse case scenarios can be identified for each task, and then summed into the project as a whole. This approach was knocked due to the amount of unnecessary planning and guesswork required.
“Eating the Elephant”, however, involves completing tiny slices of functionality, then calculating how long further iterations will take. By incrementally gaining experience, the estimate is more refined, as well as general confidence in the project.
From past experience with critical path analysis, I can see why estimates require experience. Having understood this, for future projects I’ll remember to “eat the elephant, one bite at a time”.
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