From Story Points to COSMIC Function Points in Agile Software Development - A Six Sigma perspective
Thomas Fehlmann, Luca Santillo · 2010
The spreading of agile methodologies in software development raises the question of how to measure requirements once more, as it happened in ‘traditional’ software industry development approaches decades ago. The difference is that requirements are not known in advance but detected as User Stories while iterating and enhancing the software product from one agile ‘Sprint’ to the other. Some authors – promoting best practices for agile software development – propose Story Points to size User Stories (e.g., Scrum, with Story Cards), yet not combined with base project estimation. Story Points are not standardized, thus leading to eventual misconceptions and quantitative differences among practitioners and domains. The uncertainty implied in such approach can therefore propagate to any estimate based on it, not to mention the difficulty in accurately tracing requirements and their variation over the project and across project iterations. This work investigates benefits from adopting a standardized Functional Size Measurement (FSM) method, such as COSMIC Function Points, in place of Story Points. Using a Transfer Function (from the Six Sigma practice) that transforms size into effort spent within a particular agile team, defect density prediction can be made using sensitivity analysis.