D/2004/7012/20 Comparative Evaluation of Functional Size Measurement Methods: An Experimental Analysis

Abstract − A number of Functional Size Measurement (FSM) methods have been proposed in the literature, but so far there has been no systematic evaluation of these methods. A major criticism is that little attention has been paid to the empirical validation of FSM methods. By empirical validation we refer to the evaluation of the efficacy of the method and its likely adoption in practice using experimental techniques and statistical data analysis. This paper describes a laboratory experiment which compares Function Points Analysis, a standard FSM method supported by the International Functional Point Users Group (IFPUG FPA) and OO-Method Function Points (OOmFP), a recently proposed FSM method for sizing object-oriented (OO) software systems that are developed using the OO-Method approach. The goal is to investigate whether OOmFP results in better size assessments and is more likely to be adopted in practice, within the context of an OO-Method development process. As OOmFP and IFPUG FPA are FSM methods, only the functional size of a software system is quantified, meaning that only the functional system requirements as seen from the user’s perspective are considered as contributing to system size. The methods are compared using a range of performance-based and perception-based variables, includin