- Be extremely aware of the underlying assumptions implicit in your estimation process.
- Only the people who will actually perform the work are qualified to estimate how long it will take them to perform a given task within the context of your project..
- You should be developing your estimates with the active cooperation of the people who will actually be producing the work increment.
Beware of False Equivalencies
Any suggestions on how to proceed other than relying on the SMEs to estimate previous durations/workhours for similar documents?
One of the central tenets of effective estimation is that only the people who will actually perform the work are qualified to estimate how long it will take them to perform a given task. Rather than looking at other projects, or asking subject-matter experts who may not be directly involved in the project, you should be developing your estimates with the active cooperation of the people who will actually be producing the work increment. By trying to bypass task-performers for the estimation, you run the risk of applying invalid estimates to your schedule.
By applying estimates of tasks performed by other people, you are making several implicit assumptions:
- You cannot trust the estimates of the task performers on your project.
- The work done by someone else is equivalent to the work to be done within your project.
- The skills and resources within your project team are equivalent to the "prior art" project you are using as your baseline.
- The context in which the work will be done is functionally equivalent between projects and organizations.
Think of it this way: if Alice could perform a task in one day, but Bob will take three days, it really doesn't matter that it takes Alice 66% less time to perform the task because she isn't on your project team—Bob is, and accurate scheduling is about estimating based on Bob's capabilities to get the work done.
Basing work-effort on something other than the skills and resources actually at hand is really setting a management target rather than developing a valid estimate. It may simply not be a valid estimate for your team, and assuming that it is will likely lead to a post-mortem blame-game rather than a finished set of deliverables.
Your mileage may vary. That's the point. :)