Unified Model of Functional Size Measurement

Functional Size Measurement (FSM) is one of the most important parts of software measurement research. In response to different users´ needs, organizations may measure software size using different FSM methods. In order to measure software simultaneously by more than one FSM methods, this paper discusses three common FSM methods (IFPUG FPA, COSMIC FFP and MarkII FPA), gives a unified model of functional size measurement (FSM-UM) and proposes the mapping rulers of FSM-UM to the three FSM methods. Moreover,this paper provides a case study using FSM-UM in brief.