Software Estimation Without Guessing

The Parametric Model Approach

Sometimes a linear model seems too simplistic. Progress depends on more than the passage of time. There are so many variables that a linear model ignores, and surely these variables have an effect. Of course, if the variables are constant in the reference system and the system being estimated, they don’t need to be explicitly modeled. They’re implicitly included in the reference system.

If some of the variables differ between your reference system and the system being estimated, though, then it may well be worthwhile to account for them. That’s especially true if these variables change over time during the project. If you double the number of people working on the project halfway through, you don’t expect your ...