8.4 Using Project Data to Refine Your Estimates

Earlier in this chapter, I pointed out that historical data is useful because it accounts for organizational influences—both recognized and unrecognized. The same idea applies to the use of historical data within a specific project (Gilb 1988, Cohn 2006). Individual projects have dynamics that will vary somewhat from the dynamics of their surrounding organizations. Using data from the project itself will account for the influences that are unique to that specific project. The sooner on a project you can begin basing your estimates on data from the project itself, the sooner your estimates will become truly accurate.

Tip #40

Use data from your current project (project data) to create highly accurate estimates for the remainder of the project.

Even if you don't have historical data from past projects, you can collect data from your current project and use that as a basis for estimating the remainder of your project. Your goal should be to switch from using organizational data or industry-average data to project data as soon as you can. The more iterative your project is, the sooner you'll be able to do this.

Collecting and using data from your own project will be discussed in more detail in Section 16.4, "Estimate Refinement." Section 12.3, "Story Points," presents a specific example of using project data to refine your estimates.