Estimating the solution

With your Work Breakdown Structure in hand, you can start estimating the real work involved in each group of tasks. Estimate the effort needed to perform the task in hours or days (measured in ideal engineering hours, assuming concentrated, uninterrupted work on the task). Don't fall into the trap of estimating in duration—duration estimates will vary wildly depending on how much non-project work the person doing the estimate expects to be doing at the same time.

Tip

Use small tasks

If you find that a work package has an estimate of more than 80 hours, revisit the Work Breakdown Structure and split the task into smaller subtasks. An estimate of 80+ hours very often indicates an incomplete understanding of the task and carries a large risk of overrunning the estimate.

The individual subsystem work packages might break the 80-hour limit and are, therefore, divided into subpackages.

Top-down estimate

If you are an experienced project manager, you can probably produce a rough...