Software metrics

Software metrics as a subject area is over 30 years old, but it has barely penetrated into mainstream software engineering. A key reason for this is that most software metrics activities have not addressed their most important requirement: to provide information to support quantitative managerial decision-making during the software lifecycle. Good support for decision-making implies support for risk assessment and reduction. Yet traditional metrics approaches, often driven by regression-based models for cost estimation and defects prediction, provide little support for managers wishing to use measurement to analyse and minimise risk. The future for software metrics lies in using relatively simple existing metrics to build management decision-support tools that combine different aspects of software development and testing and enable managers to make many kinds of predictions, assessments and trade-offs during the software life-cycle. Our recommended approach is to handle the key factors largely missing from the usual metrics approaches, namely: causality, uncertainty, and combining different (often subjective) evidence. Thus the way forward for software metrics research lies in causal modelling (we propose using Bayesian nets), empirical software engineering, and multi-criteria decision aids.