COSMIC Function Points Evaluation for Software Maintenance

The Common Software Measurement International Consortium (COSMIC) group reviewed the existing functional size methods, such as the International Function Points User Group (IFPUG)'s Function Points (FPs), to develop a functional size metric based on "the basic principles" that applies to a wide range of application domains. Though several empirical studies on the COSMIC method verify that COSMIC Function Points (CFPs) successfully accomplished the goal of being applicable to a wide range of application domains and that its size correlate well with effort over a very wide range of sizes, one study of telecom switching software noticed that the correlation between CFPs and cost is very low for small projects (5 CFPs or less). The COSMIC method does not explicitly size data manipulations (such as, mathematical algorithms), which causes it to be less effective for mathematically-intensive software. IFPUG's FPs method has the same drawback of not explicitly measuring mathematical operations, but IFPUG developed the Software Non Functional Assessment Process (SNAP) to complement a project's functional size. This empirical analysis will determine whether CFPs can be an effective size metric for small, maintenance tasks (between 2 and 12 CFPs) using a dataset consisting of Unified Code Count (UCC)(1)'s maintenance tasks. Additionally, this analysis will consider whether using IFPUG's SNAP with COSMIC's FPs can lead to better effort estimates, as the former provides a method to measure data manipulation. The authors found that tasks adding new features require a different effort estimate model from those that modify existing features.