An experimental study on the conversion between IFPUG and COSMIC functional size measurement units

The adoption of functional size measurement (FSM) methods in software organizations is growing. In particular, special attention is being paid to the COSMIC method, because of its novelties against 1st generation FSM methods such as IFPUG FPA. One of the main problems facing organizations wanting to use COSMIC is how to properly convert the software functional size of the projects in their portfolio measured by the previously adopted FSM method to the size measured by the new method. The objective of this paper is to find a sound mathematical basis for converting an IFPUG measurement to a COSMIC measurement. In the light of previously published researches, parallel measurements were performed to establish three new datasets (respectively composed by 21, 14 and 35 data points) and verified by an expert measurer, certified on both techniques. In order to obtain a more precise solution, the search for a mathematical relationship has been run using new nonlinear equation types. Results from the analysis confirmed an approximated conversion factor of 1:1. within a range between 0.9 and 1.1, but moving from a larger number of data points analyzed then in past studies. These results can be very useful for those companies starting to use their benchmarking databases populated in IFPUG FP units to projects measured in COSMIC FP. (c) 2009 Elsevier B.V. All rights reserved.