An Empirical Illustration to Validate a FLOSS Development Model Using S-Shaped Curves

Open source software (OSS) or Free/Libre OSS (FLOSS) has become an interesting source of research in software engineering. However, it has been criticized that FLOSS development is often considered as a homogeneous phenomenon grounded by assumptions rather than empirical evidence. Proper empirical methods that can shed light into FLOSS development are desirable. In this paper, we propose an empirical method to validate a software development model for FLOSS, the Adapted Staged Model for FLOSS. We mined some selected metrics from Apache Ivy and study their evolution using S-shaped curves. Our results indicate that S-shaped curves can model software evolution well for Ivy. Moreover, we demonstrated that our method can be used to identify successfully different stages of its development, validating part of the Adapted Staged Model for FLOSS.