arXiv subjects

Gabriele Rotoloni

Publications and source records attributed to Gabriele Rotoloni.

2 recordsLinked to original sources

arXiv2026

Evaluating Software Defect Prediction Models via the Area Under the ROC Curve Can Be Misleading

Background: Receiver Operating Characteristic (ROC) curves are widely used to evaluate the performance of Software Defect Prediction (SDP) models that estimate module fault-proneness, i.e., the probability that a module is faulty. A ROC curve maps a model's performance in terms of True Positive Rate and False Positive Rate for any possible threshold set on fault-proneness. The Area Under the ROC Curve (AUC) summarizes the performance of a model across all possible thresholds. Traditionally, ROC curves completely above the bisector of the ROC space are considered better than random, and high AUC values are associated with good performance. Aim: We investigate whether these beliefs are correct, hence if SDP model evaluation based on ROC curves and AUC is reliable. Method: We decorate ROC curves by highlighting the points corresponding to threshold values. We also represent True Positive Rate and False Positive Rate as functions of the threshold. Thus, we can evaluate whether a model classifies both faulty and non-faulty modules better than the random model. Results: We show that commonly used evaluation criteria may lead to wrong conclusions. Conclusions: A high value of AUC does not guarantee that both the True Positive Rate and the False Positive Rate of a model are better than the random model's for all possible thresholds. Either decorated ROC curves or alternative representations are needed to appreciate all the relevant aspects of SDP models.

cs.SE↗

arXiv2025

Critical Considerations on Effort-aware Software Defect Prediction Metrics

Background. Effort-aware metrics (EAMs) are widely used to evaluate the effectiveness of software defect prediction models, while accounting for the effort needed to analyze the software modules that are estimated defective. The usual underlying assumption is that this effort is proportional to the modules' size measured in LOC. However, the research on module analysis (including code understanding, inspection, testing, etc.) suggests that module analysis effort may be better correlated to code attributes other than size. Aim. We investigate whether assuming that module analysis effort is proportional to other code metrics than LOC leads to different evaluations. Method. We show mathematically that the choice of the code measure used as the module effort driver crucially influences the resulting evaluations. To illustrate the practical consequences of this, we carried out a demonstrative empirical study, in which the same model was evaluated via EAMs, assuming that effort is proportional to either McCabe's complexity or LOC. Results. The empirical study showed that EAMs depend on the underlying effort model, and can give quite different indications when effort is modeled differently. It is also apparent that the extent of these differences varies widely. Conclusions. Researchers and practitioners should be aware that the reliability of the indications provided by EAMs depend on the nature of the underlying effort model. The EAMs used until now appear to be actually size-aware, rather than effort-aware: when analysis effort does not depend on size, these EAMs can be misleading.

cs.SE↗