Three Parts of Estimation

The Pragmatic Manager, Volume 1 #1


  • This month's Feature Article: Three Parts of Estimation
  • On the Bookshelf
  • Want to hear more from Johanna?
  • Want to read more of Johanna's writing?


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. 1. Giving a date range for the estimate: ?We’ll be able to release between May 1 – June 15.?
  2. Using ?about? to describe the precision of the estimate: ?5 people for about 9 months or 10 people for about 6 months.”
  3. 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.


  • On the Bookshelf:

I'm reading two books right now:

Luke Hohmann's “Beyond Software Architecture: Creating and Sustaining Winning Solutions”, ISBN 0-201-77594-8. If you've ever had to interact with product management, or had to decide if the architecture was any good, you want to read this book. It's full of gems like this one, “How many people will it cost to replace this thing?” Luke says that if you could replace the architecture with half the team in one year, you should consider it. And then he explains why.

Tom DeMarco and Tim Lister have another fabulous book in “Waltzing with Bears: Managing Risk on Software Projects”, ISBN ISBN: 0-932633-60-9. It's full of terrific ideas, such as how to brainstorm risks on a project — at the beginning. After all, as the authors say, “If There's No Risk On Your Next Project, Don't Do It.”


  • Want to hear more from Johanna?

If you want to catch me at a public event, see if you can make these:

  • Mar 26-27: Software Development West, Santa Clara, CA. “Effective Metrics for Pragmatic Project Managers” and “Successful Software Management: 13 Lessons Learned”
  • Mar 31-Apr 2: SPC, Vancouver BC: “Advanced Topics in Project Management”, “Everything Project Managers Need to know about Requirements…”, and “Negotiating Your Way to Project Success”
  • April 10: Boscon, Burlington, MA, “Release Criteria: Defining the Rules of the Product Release Game”
  • April 14: PMI Great Lakes Chapter, “Project Checkup: Pragmatic Metrics for Healthy (and not-so-healthy) Projects”

If you're considering conferences this year, I hope you choose the Software Management conference in the spring and the AYE conference in the fall.

I served as the program chair for the SM part of the conference for two years, and this year I'm giving a talk on how to hire people. If you manage people, or you're thinking about managing people, you're dealing with management problems, this is the conference for you. SQE has a sign-up on their web page for their events.

I've been a host of the AYE conference for the past three years, and this year registrations are already coming in fast and furious. I haven't completely decided what to present there yet, but I will be repeating the writer's and speaker's workshops with Naomi Karten. See for more information.


  • Want to read more of Johanna's writing?

I've joined the ranks of the bloggers, with Managing Product Development, and Hiring Technical People.

I keep a list of my latest writings and point to the articles from there.

  • My latest columns in Software Development: Shaking off the “Shoulds” Part 1, and Pardon Sisyphus, Part 2, Software Development, January and February, 2003
  • STQE: Clarify Your Ranking for System Problem Reports,, March 2003
  • What's Wrong with Wednesday?, January 2003
  • Ready, Aim….Hire” is in STQE this month.


If you'd like some common sense, down-to-earth ideas about how to manage projects, people, or your work, you've come to the right place. Each e-zine has a short feature article and other information you can use to work better.

Tell me how you've used these ideas. Or, if you have questions, comments, or feedback, tell me that too.

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