Privacy preserving via interval covering based subclass division and manifold learning based bi-directional obfuscation for effort estimation

When a company lacks local data in hand, engineers can build an effort model for the effort estimation of a new project by utilizing the training data shared by other companies. However, one of the most important obstacles for data sharing is the privacy concerns of software development organizations. In software engineering, most of existing privacy-preserving works mainly focus on the defect prediction, or debugging and testing, yet the privacy-preserving data sharing problem has not been well studied in effort estimation. In this paper, we aim to provide data owners with an effective approach of privatizing their data before release. We firstly design an Interval Covering based Subclass Division (ICSD) strategy. ICSD can divide the target data into several subclasses by digging a new attribute (i.e., class label) from the effort data. And the obtained class label is beneficial to maintaining the distribution of the target data after obfuscation. Then, we propose a manifold learning based bi-directional data obfuscation (MLBDO) algorithm, which uses two nearest neighbors, which are selected respectively from the previous and next subclasses by utilizing the manifold learning based nearest neighbor selector, as the disturbances to obfuscate the target sample. We call the entire approach as ICSD&MLBDO. Experimental results on seven public effort datasets show that: 1) ICSD&MLBDO can guarantee the privacy and maintain the utility of obfuscated data. 2) ICSD&MLBDO can achieve better privacy and utility than the compared privacy-preserving methods.