Use All Four Parts of Project Estimation

©2004 Johanna Rothman.

Project work estimation has three components: the initial first cut, commonly known as a SWAG (Scientific Wild Ass Guess), tracking the estimate against the actuals, and using the schedule to see what’s happening in your project.

If you’ve been assigned project estimates, or if your project estimates aren’t particularly close to reality, don’t fret. Try these techniques to estimate and learn about your estimates.

Part 1: Create an Initial Estimate

If you’re a project manager, you probably try to estimate the work at the beginning of the project, even if you’re assigned a project end date. Sometimes, senior managers have trouble hearing what you’ve said in your estimate. I use one of these three alternatives to creating estimates for the entire project:

1. Provide a date range for the estimate: “We’ll be able to release between May 1 – June 15.” Some senior managers can’t hear the second half of that statement; they only hear May 1. If you work for a manager like that, try either of these other two suggestions.

2. Use the word “about” to describe the precision of the estimate: “5 people for about 9 months or 10 people for about 6 months.” You haven’t described an end date, but you have explained the resources you’ll require.

3. Provide a confidence level to describe the range of dates: “I have 90% confidence in June 1 and 100% confidence in August 1.” In my experience, even the managers who can;t hear the “between” estimate can hear my confidence levels.

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 project estimate.

The problem with estimates is that they are guesses. They’re the best guesses we can make, 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 and to know how to update your estimates, with the second part of estimation, the EQF, Estimation Quality Factor.

Part 2: Track EQF to Understand the Project Estimate

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. People tend to work on what you, the project manager focuses on. 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.

When you track EQF with your project team, you’re learning more about the project, and using EQF to learn how good your initial estimate was.

Part 3: Use EQF to Manage Project Concerns

I use 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 with the project team.

And, once I understand the project team’s concerns, I can deal with them or elevate those concerns to my management.

Part 4: Update Your Estimate as You Know More

When you first created an estimate, you developed some date range, an “about” date, or a series of dates with a confidence level. Once the project is underway and you’re using EQF to understand what the rest of the project team thinks of the date and the risks to the project, you’re ready to update your project estimate.

If the team has missed interim milestones and all of you think there is no way to deliver the requested feature set in the estimated time with appropriate defect levels, then it’s time to slip the project. Remember, don’t slip a week every week; that’s an out of control project. Instead, make the slip as long as you need it. Manage the risks of further slippage by creating more interim deliverables.

If the team has met their milestones, and you’re on track, you can close in on a more specific date. For example, if you started with a completion date of “May 1 – June 15,” about halfway through the project you might be able to say, “May 8 – June 10.” About three quarters of the way through the project you can probably say, “May 20 – June 1.” As you reach May 1, you can say when in those ten days you can complete the project.

Summary

If you’re only using one of these techniques to estimate and manage your projects, consider adding the others. Every project worth completing has some project uncertainty. EQF is a great technique for displaying project uncertainty, and understanding why the project team is uncertain about the project.

The more everyone understands about the project, the better your project management will be, and the more likely you are to meet your SWAG. At least, you’ll know how far off your SWAG was, and why. And that knowledge can help you on your next project.

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