A transfer cost-sensitive boosting approach for cross-project defect prediction

Software defect prediction has been regarded as one of the crucial tasks to improve software quality by effectively allocating valuable resources to fault-prone modules. It is necessary to have a sufficient set of historical data for building a predictor. Without a set of sufficient historical data within a company, cross-project defect prediction (CPDP) can be employed where data from other companies are used to build predictors. In such cases, a transfer learning technique, which extracts common knowledge from source projects and transfers it to a target project, can be used to enhance the prediction performance. There exists the class imbalance problem, which causes difficulties for the learner to predict defects. The main impacts of imbalanced data under cross-project settings have not been investigated in depth. We propose a transfer cost-sensitive boosting method that considers both knowledge transfer and class imbalance for CPDP when given a small amount of labeled target data. The proposed approach performs boosting that assigns weights to the training instances with consideration of both distributional characteristics and the class imbalance. Through comparative experiments with the transfer learning and the class imbalance learning techniques, we show that the proposed model provides significantly higher defect detection accuracy while retaining better overall performance. As a result, a combination of transfer learning and class imbalance learning is highly effective for improving the prediction performance under cross-project settings. The proposed approach will help to design an effective prediction model for CPDP. The improved defect prediction performance could help to direct software quality assurance activities and reduce costs. Consequently, the quality of software can be managed effectively.     

Cost-sensitive transfer kernel canonical correlation analysis for heterogeneous defect prediction

Cross-project defect prediction (CPDP) refers to predicting defects in a target project using prediction models trained from historical data of other source projects. And CPDP in the scenario where source and target projects have different metric sets is called heterogeneous defect prediction (HDP). Recently, HDP has received much research interest. Existing HDP methods only consider the linear correlation relationship among the features (metrics) of the source and target projects, and such models are insufficient to evaluate nonlinear correlation relationship among the features. So these methods may suffer from the linearly inseparable problem in the linear feature space. Furthermore, existing HDP methods do not take the class imbalance problem into consideration. Unfortunately, the imbalanced nature of software defect datasets increases the learning difficulty for the predictors. In this paper, we propose a new cost-sensitive transfer kernel canonical correlation analysis (CTKCCA) approach for HDP. CTKCCA can not only make the data distributions of source and target projects much more similar in the nonlinear feature space, where the learned features have favorable separability, but also utilize the different misclassification costs for defective and defect-free classes to alleviate the class imbalance problem. We perform the Friedman test with Nemenyi’s post-hoc statistical test and the Cliff’s delta effect size test for the evaluation. Extensive experiments on 28 public projects from five data sources indicate that: (1) CTKCCA significantly performs better than the related CPDP methods; (2) CTKCCA performs better than the related state-of-the-art HDP methods.     

Predicting high-risk program modules by selecting the right software measurements

A timely detection of high-risk program modules in high-assurance software is critical for avoiding the high consequences of operational failures. While software risk can initiate from external sources, such as management or outsourcing, software quality is adversely affected when internal software risks are realized, such as improper practice of standard software processes or lack of a defined software quality infrastructure. Practitioners employ various techniques to identify and rectify high-risk or low-quality program modules. Effectiveness of detecting such modules is affected by the software measurements used, making feature selection an important step during software quality prediction. We use a wrapper-based feature ranking technique to select the optimal set of software metrics to build defect prediction models. We also address the adverse effects of class imbalance (very few low-quality modules compared to high-quality modules), a practical problem observed in high-assurance systems. Applying a data sampling technique followed by feature selection is a relatively unique contribution of our work. We present a comprehensive investigation on the impact of data sampling followed by attribute selection on the defect predictors built with imbalanced data. The case study data are obtained from several real-world high-assurance software projects. The key results are that attribute selection is more efficient when applied after data sampling, and defect prediction performance generally improves after applying data sampling and feature selection.     

基于采样的半监督支持向量机软件缺陷预测方法

软件缺陷预测有助于提高软件开发质量,保证测试资源有效分配。针对软件缺陷预测研究中类标签数据难以获取和类不平衡分布问题,提出基于采样的半监督支持向量机预测模型。该模型采用无监督的采样技术,确保带标签样本数据中缺陷样本数量不会过低,使用半监督支持向量机方法,在少量带标签样本数据基础上利用无标签数据信息构建预测模型;使用公开的NASA软件缺陷预测数据集进行仿真实验。实验结果表明提出的方法与现有半监督方法相比,在综合评价指标[F]值和召回率上均优于现有方法;与有监督方法相比,能在学习样本较少的情况下取得相当的预测性能。     

Non‐negative sparse‐based SemiBoost for software defect prediction

Software defect prediction is an important decision support activity in software quality assurance. The limitation of the labelled modules usually makes the prediction difficult, and the class‐imbalance characteristic of software defect data leads to negative influence on decision of classifiers. Semi‐supervised learning can build high‐performance classifiers by using large amount of unlabelled modules together with the labelled modules. Ensemble learning achieves a better prediction capability for class‐imbalance data by using a series of weak classifiers to reduce the bias generated by the majority class. In this paper, we propose a new semi‐supervised software defect prediction approach, non‐negative sparse‐based SemiBoost learning. The approach is capable of exploiting both labelled and unlabelled data and is formulated in a boosting framework. In order to enhance the prediction ability, we design a flexible non‐negative sparse similarity matrix, which can fully exploit the similarity of historical data by incorporating the non‐negativity constraint into sparse learning for better learning the latent clustering relationship among software modules. The widely used datasets from NASA projects are employed as test data to evaluate the performance of all compared methods. Experimental results show that non‐negative sparse‐based SemiBoost learning outperforms several representative state‐of‐the‐art semi‐supervised software defect prediction methods. Copyright © 2016 John Wiley & Sons, Ltd.     

基于深度自编码网络的软件缺陷预测方法

软件缺陷预测是提升软件质量的有效方法,而软件缺陷预测方法的预测效果与数据集自身的特点有着密切的相关性。针对软件缺陷预测中数据集特征信息冗余、维度过大的问题,结合深度学习对数据特征强大的学习能力,提出了一种基于深度自编码网络的软件缺陷预测方法。该方法首先使用一种基于无监督学习的采样方法对6个开源项目数据集进行采样,解决了数据集中类不平衡问题;然后训练出一个深度自编码网络模型。该模型能对数据集进行特征降维,模型的最后使用了三种分类器进行连接,该模型使用降维后的训练集训练分类器,最后用测试集进行预测。实验结果表明,该方法在维数较大、特征信息冗余的数据集上的预测性能要优于基准的软件缺陷预测模型和基于现有的特征提取方法的软件缺陷预测模型,并且适用于不同分类算法。     

跨项目缺陷预测中训练数据选择方法

跨项目缺陷预测（CPDP）利用来自其他项目的缺陷数据预测目标项目的缺陷情况,为解决以往缺陷预测方法面临的训练数据受限问题提供了一个新的视角。训练数据的质量将直接影响跨项目缺陷预测模型的性能,因此,需尽可能选择与目标项目更相似的数据用于模型的训练。利用PROMISE提供的34个公开数据集,从训练数据选择方面,分析了四种典型的相似性度量方法对跨项目预测结果的影响以及各种方法之间的差异。研究结果表明：使用不同的相似性度量方法选出的训练数据质量不同,其中余弦相似性与相关系数两种方法效果更好,且最大改进比例达到6.7%;同时,根据目标项目的缺陷率,发现余弦相似性更适合于缺陷率高于0.25的项目。     

结合欠抽样与集成的软件缺陷预测

软件缺陷预测是提高测试效率、保证软件可靠性的重要途径。为了提高软件缺陷预测的准确率,提出一种结合欠抽样与决策树分类器集成的软件缺陷预测模型。考虑到软件缺陷数据的类不平衡特性,首先,通过数据的不平衡率确定抽样度,执行欠抽样实现数据的重新平衡;然后,采用Bagging随机抽样原理训练若干个决策树子分类器;最后,按照少数服从多数的原则生成预测模型。使用公开的NASA软件缺陷预测数据集进行了仿真实验。实验结果表明,与3种基准方法对比,所提模型在保证预报率的前提下,误报率(PF)降低了10%以上,综合评价指标均有显著提升。该模型的缺陷预测误报率较低,而且具有较高的预测准确率与稳定性。     

Multiple kernel ensemble learning for software defect prediction

Software defect prediction aims to predict the defect proneness of new software modules with the historical defect data so as to improve the quality of a software system. Software historical defect data has a complicated structure and a marked characteristic of class-imbalance; how to fully analyze and utilize the existing historical defect data and build more precise and effective classifiers has attracted considerable researchers’ interest from both academia and industry. Multiple kernel learning and ensemble learning are effective techniques in the field of machine learning. Multiple kernel learning can map the historical defect data to a higher-dimensional feature space and make them express better, and ensemble learning can use a series of weak classifiers to reduce the bias generated by the majority class and obtain better predictive performance. In this paper, we propose to use the multiple kernel learning to predict software defect. By using the characteristics of the metrics mined from the open source software, we get a multiple kernel classifier through ensemble learning method, which has the advantages of both multiple kernel learning and ensemble learning. We thus propose a multiple kernel ensemble learning (MKEL) approach for software defect classification and prediction. Considering the cost of risk in software defect prediction, we design a new sample weight vector updating strategy to reduce the cost of risk caused by misclassifying defective modules as non-defective ones. We employ the widely used NASA MDP datasets as test data to evaluate the performance of all compared methods; experimental results show that MKEL outperforms several representative state-of-the-art defect prediction methods.     

A Cluster Based Feature Selection Method for Cross-Project Software Defect Prediction

Cross-project defect prediction (CPDP) uses the labeled data from external source software projects to compensate the shortage of useful data in the target project, in order to build a meaningful classification model. However, the distribution gap between software features extracted from the source and the target projects may be too large to make the mixed data useful for training. In this paper, we propose a cluster-based novel method FeSCH (Feature Selection Using Clusters of Hybrid-Data) to alleviate the distribution differences by feature selection. FeSCH includes two phases. The feature clustering phase clusters features using a density-based clustering method, and the feature selection phase selects features from each cluster using a ranking strategy. For CPDP, we design three different heuristic ranking strategies in the second phase. To investigate the prediction performance of FeSCH, we design experiments based on real-world software projects, and study the effects of design options in FeSCH (such as ranking strategy, feature selection ratio, and classifiers). The experimental results prove the effectiveness of FeSCH. Firstly, compared with the state-of-the-art baseline methods, FeSCH achieves better performance and its performance is less affected by the classifiers used. Secondly, FeSCH enhances the performance by effectively selecting features across feature categories, and provides guidelines for selecting useful features for defect prediction.     

Cross Project Defect Prediction via Balanced Distribution Adaptation Based Transfer Learning

Defect prediction assists the rational allocation of testing resources by detecting the potentially defective software modules before releasing products. When a project has no historical labeled defect data, cross project defect prediction (CPDP) is an alternative technique for this scenario. CPDP utilizes labeled defect data of an external project to construct a classification model to predict the module labels of the current project. Transfer learning based CPDP methods are the current mainstream. In general, such methods aim to minimize the distribution differences between the data of the two projects. However, previous methods mainly focus on the marginal distribution difference but ignore the conditional distribution difference, which will lead to unsatisfactory performance. In this work, we use a novel balanced distribution adaptation (BDA) based transfer learning method to narrow this gap. BDA simultaneously considers the two kinds of distribution differences and adaptively assigns different weights to them. To evaluate the effectiveness of BDA for CPDP performance, we conduct experiments on 18 projects from four datasets using six indicators (i.e., F-measure, g-means, Balance, AUC, EARecall, and EAF-measure). Compared with 12 baseline methods, BDA achieves average improvements of 23.8%, 12.5%, 11.5%, 4.7%, 34.2%, and 33.7% in terms of the six indicators respectively over four datasets.     

A novel modified undersampling (MUS) technique for software defect prediction

Background and aim: Many sophisticated data mining and machine learning algorithms have been used for software defect prediction (SDP) to enhance the quality of software. However, real‐world SDP data sets suffer from class imbalance, which leads to a biased classifier and reduces the performance of existing classification algorithms resulting in an inaccurate classification and prediction. This work aims to improve the class imbalance nature of data sets to increase the accuracy of defect prediction and decrease the processing time . Methodology: The proposed model focuses on balancing the class of data sets to increase the accuracy of prediction and decrease processing time. It consists of a modified undersampling method and a correlation feature selection (CFS) method. Results: The results from ten open source project data sets showed that the proposed model improves the accuracy in terms of F1‐score to 0.52 ～ 0.96, and hence it is proximity reached best F1‐score value in 0.96 near to 1 then it is given a perfect performance in the prediction process. Conclusion: The proposed model focuses on balancing the class of data sets to increase the accuracy of prediction and decrease processing time using the proposed model.     

基于混合采样与Random_Stacking的软件缺陷预测

现有的软件缺陷预测方法面临数据类别不平衡性、高维数据处理等问题。如何有效解决上述问题已成为目前相关领域的研究热点。针对软件缺陷预测所面临的类别不平衡、预测精度低等问题,本文提出一种基于混合采样与Random_Stacking的软件缺陷预测算法DP_HSRS。DP_HSRS算法首先采用混合采样算法对不平衡数据进行平衡化处理;然后在该平衡数据集上采用Random_Stacking算法进行软件缺陷预测。Random_Stacking算法是对传统Stacking算法的一种有效改进,它通过融合多个经典的分类算法以及Bagging机制构建多个Stacking分类器,对多个Stacking分类器进行投票,得到一个集成分类器,最后利用该集成分类器对软件缺陷进行预测。通过在NASA MDP数据集上的实验结果表明,DP_HSRS算法的性能优于现有的算法,具有更好的缺陷预测性能。     

一种半监督集成跨项目软件缺陷预测方法

软件缺陷预测方法可以在项目的开发初期,通过预先识别出所有可能含有缺陷的软件模块来优化测试资源的分配。早期的缺陷预测研究大多集中于同项目缺陷预测,但同项目缺陷预测需要充足的历史数据,而在实际应用中可能需要预测的项目的历史数据较为稀缺,或这个项目是一个全新项目。因此跨项目缺陷预测问题成为当前软件缺陷预测领域内的一个研究热点,其研究挑战在于源项目与目标项目数据集间存在的分布差异性以及数据集内存在的类不平衡问题。受到基于搜索的软件工程思想的启发,论文提出了一种基于搜索的半监督集成跨项目软件缺陷预测方法S³EL。该方法首先通过调整训练集中各类数据的分布比例,构建出多个朴素贝叶斯基分类器,随后利用具有全局搜索能力的遗传算法,基于少量已标记目标实例对上述基分类器进行集成,并构建出最终的缺陷预测模型。在Promise数据集及AEEEM数据集上和多个经典的跨项目缺陷预测方法（Burak过滤法、Peters过滤法、TCA+、CODEP及HYDRA）进行了对比。以F1值作为评测指标,结果表明在大部分情况下,S³EL方法可以取得最好的预测性能。     

Evolutionary Sampling and Software Quality Modeling of High-Assurance Systems

Software quality modeling for high-assurance systems, such as safety-critical systems, is adversely affected by the skewed distribution of fault-prone program modules. This sparsity of defect occurrence within the software system impedes training and performance of software quality estimation models. Data sampling approaches presented in data mining and machine learning literature can be used to address the imbalance problem. We present a novel genetic algorithm-based data sampling method, named Evolutionary Sampling, as a solution to improving software quality modeling for high-assurance systems. The proposed solution is compared with multiple existing data sampling techniques, including random undersampling, one-sided selection, Wilson's editing, random oversampling, cluster-based oversampling, Synthetic Minority Oversampling Technique (SMOTE), and Borderline-SMOTE. This paper involves case studies of two real-world software systems and builds C4.5- and RIPPER-based software quality models both before and after applying a given data sampling technique. It is empirically shown that Evolutionary Sampling improves performance of software quality models for high-assurance systems and is significantly better than most existing data sampling techniques.      

基于贝叶斯Logistic回归的软件缺陷预测研究

在软件开发初期及时识别出软件存在的缺陷,可以帮助项目管理团队及时优化开发测试资源分配,以便对可能含有缺陷的软件进行严格的质量保证活动,这对于软件的高质量交付有着重要的作用,因此,软件缺陷预测成为软件工程领域内一个研究热点。虽然人们已经使用多种机器学习算法建立了缺陷预测模型,但还没有对这些模型的贝叶斯方法进行研究。提出了无信息先验和信息先验的贝叶斯Logistic回归方法来建立缺陷预测模型,并对贝叶斯Logistic回归的优势以及先验信息在贝叶斯Logistic回归中的作用进行了研究。最后,在PROMISE数据集上与其他已有缺陷预测方法（LR、NB、RF、SVM）进行了比较研究,结果表明：贝叶斯Logistic回归方法可以取得很好的预测性能。     

面向软件缺陷预测的过采样方法

为了缓解软件缺陷预测的类不平衡问题,避免过拟合影响缺陷预测模型的准确率,本文提出一种面向软件缺陷预测的基于异类距离排名的过采样方法(HDR).首先,对少数类实例进行3类实例区分,去除噪声实例,减少噪声数据导致的过拟合的情况,然后基于异类距离将实例进行排名,选取相似度高的实例两两组合产生新实例,以此来提升新实例的多样性,...     

基于多核字典学习的软件缺陷预测

提出一种多核字典学习方法,用以对软件模块是否存在缺陷进行预测。用于软件缺陷预测的历史数据具有结构复杂、类不平衡的特点,用多个核函数构成的合成核将这些数据映射到一个高维特征空间,通过对多核字典基的选择,得到一个类别平衡的多核字典,用以对新的软件模块进行分类和预测,并判定其中是否存在缺陷。在NASA MDP数据集上的实验表明,与其他软件缺陷预测方法相比,多核字典学习方法能够针对软件缺陷历史数据结构复杂、类不平衡的特点,较好地解决软件缺陷预测问题。     

软件缺陷预测中的数据预处理方法

软件缺陷预测是软件质量保障领域的热点研究课题,缺陷预测模型的质量与训练数据有密切关系。用于缺陷预测的数据集主要存在数据特征的选择和数据类不平衡问题。针对数据特征选择问题,采用软件开发常用的过程特征和新提出的扩展过程特征,然后采用基于聚类分析的特征选择算法进行特征选择;针对数据类不平衡问题,提出改进的Borderline-SMOTE过采样方法,使得训练数据集的正负样本数量相对平衡且合成样本的特征更符合实际样本特征。采用bugzilla、jUnit等项目的开源数据集进行实验,结果表明：所采用的特征选择算法在保证模型F-measure值的同时,可以降低57.94%的模型训练时间;使用改进的Borderline-SMOTE方法处理样本得到的缺陷预测模型在Precision、Recall、F-measure、AUC指标上比原始方法得到的模型平均分别提高了2.36个百分点、1.8个百分点、2.13个百分点、2.36个百分点;引入了扩展过程特征得到的缺陷预测模型比未引入扩展过程特征得到的模型在F-measure值上平均提高了3.79%;与文献中的方法得到的模型相比,所提方法得到的模型在F-measure值上平均提高了15.79%。实验结果证明所提方法能有效提升缺陷预测模型的质量。     

Software defect prediction using cost-sensitive neural network

The software development life cycle generally includes analysis, design, implementation, test and release phases. The testing phase should be operated effectively in order to release bug-free software to end users. In the last two decades, academicians have taken an increasing interest in the software defect prediction problem, several machine learning techniques have been applied for more robust prediction. A different classification approach for this problem is proposed in this paper. A combination of traditional Artificial Neural Network (ANN) and the novel Artificial Bee Colony (ABC) algorithm are used in this study. Training the neural network is performed by ABC algorithm in order to find optimal weights. The False Positive Rate (FPR) and False Negative Rate (FNR) multiplied by parametric cost coefficients are the optimization task of the ABC algorithm. Software defect data in nature have a class imbalance because of the skewed distribution of defective and non-defective modules, so that conventional error functions of the neural network produce unbalanced FPR and FNR results. The proposed approach was applied to five publicly available datasets from the NASA Metrics Data Program repository. Accuracy, probability of detection, probability of false alarm, balance, Area Under Curve (AUC), and Normalized Expected Cost of Misclassification (NECM) are the main performance indicators of our classification approach. In order to prevent random results, the dataset was shuffled and the algorithm was executed 10 times with the use of n-fold cross-validation in each iteration. Our experimental results showed that a cost-sensitive neural network can be created successfully by using the ABC optimization algorithm for the purpose of software defect prediction.