Temporal complexity and software faults

Software developers use complexity metrics to predict development costs before embarking on a project and to estimate the likelihood of faults once the system is built. Traditional measures, however, were designed principally for sequential programs, providing little insight into the added complexity of concurrent systems or increased demands of real-time systems. For the purpose of predicting cost and effort of development, the CoCoMo model considers factors such as real-time and other performance requirements; for fault prediction, however, most complexity metrics are silent on concurrency. An outline for developing a measure of what we term temporal complexity, including significant and encouraging results of preliminary validation, is presented. 13 standard measures of software complexity are shown to define only two distinct domains of variance in module characteristics. Two new domains of variance are uncovered through 6 out of 10 proposed measures of temporal complexity. The new domains are shown to have predictive value in the modeling of software faults