Software metrics: An overview of an evolving methodology

A direct, algorithmic software metric is a rule for assigning a number or identifier to software. It is calculated algorithmically from the software alone. This paper describes (with examples) lines of code, cyclomatic complexity v(G), average nesting depth, and the software science length, effort, and time metrics. Software metrics that are to be used for time, cost, or reliability estimates should be validated statistically via data analyses that take into consideration the application, size, implementation language, and programming techniques employed. Such research should concentrate on metrics useful for large programs. Those that work for some languages may work for similar languages as well, i.e., those in the same “family”. Observing and measuring the work of professional programmers constructing software is probably the best means to conduct this type of analysis. We propose that this be a true joint effort, with early involvement between researchers and practitioners to establish what to measure and how to measure them. The critical need is for software metrics that can be calculated early in the software development cycle to estimate the time and cost involved in software construction.