The ISO/IEC 141143-6:2012 Standard for functional size measurement Productivity Measurement of software projects. There are five functional size measurement methods in compliance with ISO/IEC standards.
- NESMA function points (ISO/IEC 24570)
- IFPUG function points (ISO/IEC 20926);
- COSMIC function points (ISO/IEC 19761)
- Mark II function points (ISO/IEC 20968)
- FiSMA function points (ISO/IEC 29881)
One of more of these measurement methods can be used to estimate agile software development and identify functional size methods for measuring productivity that provides:
- Objective, repeatable, verifiable, defensible way to determine the size of the
software. - A clear relation between functional size and effort needed to realize the application. This has been studied and verified many times.
- The measure is clear for both customer organizations and supplier organizations. More functionality means more value, more effort needed and a higher price.
- Functional size is independent of the technical solution and/or the non-functional requirements. An application of 500 NESMA function points realized in Java is just as big as a Wordpress website of 500 Function Points. This enables comparison and benchmarking over technical domains and the use of historical project data (when properly classified) in estimating new software projects.
There are other functional sizing methods. But they are nonstandard and difficult to use in practice [1]
- Story points (SP) in agile projects: A very subjective measure that only has value within one team. Comparison to other teams, departments and organizations is not possible. Please note that SPs are useful to plan sprints and to track velocity for one team, but for productivity measurements, SPs are close to useless.
- Use Case Points (UCP): Only applicable when the documentation consists of Use Cases. UCP is also a highly subjective method, especially when it comes to establishing the Technical Complexity Factor and the Environmental Factor. Also, there is no standard way to write use cases.
- Complexity Points: Subjective and no standardized method to measure the complexity of an application.
- IBRA Points: Not a standardized method to measure the business rules in an application. When applied according to the manual, the result is zero for all applications.
- Fast Function Points (FFPA) (by Gartner): A measurement method deployed by Gartner that cannot be compared to the ISO standardized function point analysis methods. FFPA is perceived to be a commercial method that lacks a theoretical base and is partly subjective. The method has not proved to be faster than the Nesma estimated method and has not proved to be more accurate. Unfortunately, it is often pushed on higher management level without the support of the specialists who have to work with it.
[1] Productivity Measurement of Software Projects Practical guide, ISBSG
