The estimating process for project cost and schedule is usually one of the poorest skills for the project. Not because it is difficult or even because it is not well understood. But because there is a myth that estimating is not really possible.
Estimating cost and schedule requires skill, experience, and a method (there are many) and some tools. Here's how it starts:
- You must have some notion of what done looks like. This can be "done" for this iteration. Or "done" for this rolling wave. Or "done" for this release.
- You must be capable of controlling the scope of "done" within the period of performance of the development process.
- You must measure productivity - the capacity for work - in some unit that allows you to forecast future performance.
- You must be able to engage everyone in a conversation about estimating the future using the past.