The Pragmatic Manager, Volume 1 #1
Feature Article: Three Parts of Estimation
Project work estimation has three components: the initial first cut, commonly known as a SWAG (Scientific Wild Tush Guess), tracking the estimate against the actuals, and using the schedule to see what's happening in your project.
Part 1: Initial Estimate
If you’re a project manager, you try to estimate the work at the beginning of the project. In a previous Reflections newsletter, Volume 5 Number 2, I suggested three alternatives to creating great estimates for the entire project:
- 1. Giving a date range for the estimate: “We’ll be able to release between May 1 – June 15.”
- Using “about” to describe the precision of the estimate: “5 people for about 9 months or 10 people for about 6 months.”
- Using a confidence level to describe the range of dates: “I have 90% confidence in June 1 and 100% confidence in August 1.”
Once you have a gross estimate at the beginning of the project, you can drill down and create estimates for each of the project components. Whether you try to create precise estimates, or choose to use slack buffers to deal with incomplete estimates, you will have some sort of total, a project estimate.
The problem with estimates is that they are guesses. The best guesses we can make, and as good as we can make them, and they are still guesses. As the project unfolds, you will be able to acquire feedback on how well you estimated, with the second part of estimation, the EQF, Estimation Quality Factor.
Part 2: Tracking EQF
As you continue to manage the project, track your initial completion date estimate. Each month, or in a short project, each week, take 5 minutes out of your project team meeting, and ask: “When do you think we will finish the project?” Track that estimate on a chart set up with the release dates on the Y-axis, and the date that you asked the question on the X-axis.
There are two good reasons for asking this question. First, you continue to focus your project staff on completing the project. Second, by asking your project staff, you can discover the various confidences the staff has in the release date. When you look at the EQF chart, you can see if people are concerned that the project will not meet its release date, or if they are feeling confident about meeting or beating the release date. Then you can deal with their concerns or your concerns.
Part 3: Using EQF to deal with project concerns
I like using the slope of the EQF to ask questions like, “Tell me what’s happened in the project to make you think we will meet/beat/miss the date.” When people become more optimistic or pessimistic, I want to know why. The EQF not only gives me feedback on my initial estimate, it gives me another technique to discuss the project state.
EQF is a great technique for managing project uncertainty, and understanding why you are uncertain about the project.
For more information, see Tom DeMarco’s book, Controlling Software Projects, ISBN: 0131717111, for the original discussion of EQF.