Concepts: Estimating Project Effort
Topics
Introduction
One of the most common desires in software development projects is to accurately determine in advance the total cost of the project. With cost and schedule overruns being the industry norm, that desire is understandable. However, the current state of software development practice isn't a predictive science, as clearly evidenced by the vast array of project failures.
That said, it is still useful to attempt some estimation of project costs, then calibrate those estimates based on actual findings as the project progresses. Here are some techniques that you may find useful in estimating software project costs.
Use-Case Points
This technique originated from on work done at Objective Systems SF AB, and was first proposed in a 1993 paper by Gustav Karner entitled Resource Estimation for Objectory Projects. This technique enables the estimation of the resources needed to develop a software system by using the elements of the use-case model as a basis for that estimation. The use-case points (UCP) that are derived from this method can then be used to determine the equivalent function point (FP) count. Function Points (FP) are a common technique for estimations, proposed by Albrecht A. J. (1979), Measuring application development productivity.
For more information, see the Whitepaper: The Estimation of Effort Based on Use Cases.
Wideband Delphi
Originating at the Rand Corporation in 1948, this technique began as the Delphi estimation method. The basic technique called upon a small team of experts to anonymously generate individual estimates from a problem description and reach consensus on a final set of estimates through iteration.
In the early 1970s, Barry Boehm and his Rand colleagues extended the basic method to include more estimation team interaction, which resulted in the Wideband Delphi method; see Software Engineering Economics. [BOE81]. Mary Sakry and Neil Potter of The Process Group, a Dallas, Texas-based consulting company, later created a repeatable procedure for performing Wideband Delphi estimation on software projects. This guideline explains that procedure.
For more Information, see the Guideline: Estimating Effort Using the Wideband Delphi Technique.
