Analytical Convertibility of Functional Size Measures: A Tool-based Approach

Background: Several Functional Size Measurement methods have been introduced after the success of Function Point Analysis, thus originating the problem of converting Function Point measures into other units. To this end, several methods -- ranging from statistical analysis to "manual" conversion -- have been used. However, none of the proposed conversion methods guarantees the necessary accuracy. Objectives: The objective of the work reported here is to define a seamless and cheap procedure that allows measurers to derive functional size measures expressed in COSMIC Function Points from size measures expressed in Function Points. Method: To get accurate conversions, we propose to exploit all the available information provided by the measurement process, that is, not only the size in Function Points, but also the details of basic functional components. To make the procedure efficient, a mapping of Function Point Analysis concepts onto COSMIC concepts is proposed. Results: A conversion procedure based on the aforementioned mapping is proposed. Such procedure is supported by a software tool that eases the conversion process. The usage of both the procedure and tool is illustrated via an example of realistic complexity. Conclusion: The proposed procedure and tool can be effectively used to perform the required measurement with very good accuracy. The tool can also be used to perform a sort of "double" measurement, i.e., both Function Points and COSMIC Function Points are measured at the same time.