A Structured Framework for Software Metrics Based on Three Primary Metrics

This paper presents a structured unifying framework for software metrics (numerical software measurements), based on the three "primary metrics" of function points (FP), person-months (PM), and lines of code (LOC). The framework is based on a layered model, with the three primary metrics constituting the lowest layer. An important property of the primary metrics, referred to as the "convertibility property" is that a primary metric can easily be converted to another primary metric. Time is also included in this layer as a fundamental (not necessarily software) primary metric. The second layer consists of general-purpose metrics such as productivity measures, which are computed from the primary metrics, and the third layer consists of specialpurpose metrics such as reliability and quality measures. This third layer is inherently extensible. The framework readily lends itself for use in both instructional and practitioner environments.