According to research conducted by Capers Jones the average amount that a software project’s scope expands from the time when the specifications are approved to the time when the system is delivered is:
- 10% to 15% for small systems,
- 30% to 35 % for large systems.
This “scope creep” or expansion of the functionality usually occurs because either:
- The systems users are able to persuade the systems developers to add various “bells and whistles” enhancements, or
- Parts of the specifications were vague in the first place, and full exploration of their implications causes significant additional work to be added project.
The solution to scope creep has three parts:
- Develop sufficiently complete and detailed specifications in the first place, to remove vagueness, ambiguities and room for misinterpretation,
- Ensure that the customers (users of the future system) participate meaningfully in development of the specifications, and fully understand them and their implications, and
- Carefully manage the change control process.
We will discuss what constitutes “sufficiently complete” specifications, meaningful participation, and management of the change control process in future posts.