Conversion of adverse data corpus to shrewd output using sampling metrics

Artificial Intelligence, particularly machine learning (ML) algorithms, plays a crucial role in detecting cyberattacks, including anomalies and intrusions. However, machine learning models trained on imbalanced cybersecurity datasets often struggle to accurately detect minority data instances and potential threats, thereby weakening overall system security. Despite extensive research, a persistent challenge is the inadequate explanation for model predictions concerning minority data classes. This study aims to address these limitations by developing a generative AI-based approach to manage minority classes in anomaly detection, incorporating concept drift handling and explainability analysis. We introduce an over-sampling technique, CGGReaT, designed to enhance the presence of minority classes in the anomaly detection domain. Leveraging Large Language Models (LLMs) as a hybrid approach, we use pre-trained transformer-based LLM DistilGPT-2 for generating synthetic tabular data. Extensive experiments on two publicly available benchmark datasets, UNSW NB15 and CIC-IDS2017, underscore the efficacy of our proposed approach. We employed concept drift detection and adaptation techniques to maintain reliable and sustainable ML performance. To enhance interpretability, eXplainable Artificial Intelligence (XAI) methods, including SHAP and LIME, are employed to quantify feature contributions to model outputs. Extensive experiments reveal that testing ML algorithms on datasets balanced with synthetic samples generated by cGGReaT boosts the prediction accuracy on the UNSW NB15 and CIC-IDS2017 datasets, compared to classifiers tested on imbalanced datasets.

The imbalanced data refer to datasets where the number of samples in one class (majority class) is much higher than the other (minority class) causing biased classifiers in favor of the majority class. Currently, it is difficult to develop an effective model using machine learning algorithms without considering data preprocessing to balance the imbalanced data sets. In this paper, we propose a Relevant Information-based under-sampling (RIS) approach to improve the classification performance for the minority class by selecting the most relevant samples from the majority class as training data. Our RIS approach is based on a self-organizing principle of relevant information, which allows extracting the underlying structure of the majority class preserving different levels of detail of the original data with a smaller number of samples. Additionally, the RIS captures the data structure beyond second order statistics by estimating information theoretic measures which quantify the statistical structure of the majority class accurately, decreasing the consequences of the imbalanced classes distribution problem. We test our methodology on synthetic and real-world imbalanced datasets. Finally, we use a cross-validation scheme to quantify the classifier performance by evaluating the geometric mean. Results show that our proposal outperforms the state of the art methods for imbalanced class distributions regarding classification geometric mean, especially in highly imbalanced datasets.

Learning from imbalanced data sets, where the number of examples of one (majority) class is much higher than the others, presents an important challenge to the machine learning community. Traditional machine learning algorithms may be biased towards the majority class, thus producing poor predictive accuracy over the minority class. In this paper, we describe a new approach that combines boosting, an ensemble-based learning algorithm, with data generation to improve the predictive power of classifiers against imbalanced data sets consisting of two classes. In the DataBoost-IM method, hard examples from both the majority and minority classes are identified during execution of the boosting algorithm. Subsequently, the hard examples are used to separately generate synthetic examples for the majority and minority classes. The synthetic data are then added to the original training set, and the class distribution and the total weights of the different classes in the new training set are rebalanced. The DataBoost-IM method was evaluated, in terms of the F-measures, G-mean and overall accuracy , against seventeen highly and moderately imbalanced data sets using decision trees as base classifiers. Our results are promising and show that the DataBoost-IM method compares well in comparison with a base classifier, a standard benchmarking boosting algorithm and three advanced boosting-based algorithms for imbalanced data set. Results indicate that our approach does not sacrifice one class in favor of the other, but produces high predictions against both minority and majority classes.

Background: Class imbalance is often discussed as a strenuous task in the realm of sentiment analysis. In an imbalanced classification, few minority class instances are unable to provide sufficient information, therefore direct learning from an unbalanced dataset can produce unsatisfactory results. This work aims to address the problem of class imbalance. Methods: At primary level this study uses a novel Synthetic Minority Oversampling Technique (SMOTE) for balancing the dataset and then proposes an ensemble model, named Ensemble Bagging Support Vector Machine (EBSVM) for opinion mining. To measure the performance of the particular approach, numerous analyses are conducted on both imbalanced and balanced datasets. Then the work compares the effectiveness of the suggested model with three base classifiers (Nave Bayes (NB), Decision Tree (DT), and Support Vector Machine (SVM)). The customer reviews for restaurants is chose as the dataset for this work. Accuracy, precision, recall and F-measure are used as metrics for evaluation. Findings: According to the results, the suggested EBSVM model excels all other individual classifiers with the imbalanced and SMOTE balanced dataset. The balanced EBSVM classifier improves the imbalanced EBSVM Classifier in terms of accuracy. Precision, recall and F-measure of the minority class in the imbalanced classifiers have been improved in balanced Classifiers. Novelty: The performance of opinion mining classifiers for imbalanced and balanced datasets is evaluated in this paper. The work examines not only general opinions, but also specific aspects such as food, service, ambiance, quality, and price. Comparing the suggested model with existing classification algorithms in the literature, it has found that it outperformed the other models. Keywords: Bagging; Accuracy; Ensemble; Precision; Recall; Fmeasure

Classification of imbalanced data set is a challenging problem as it is very difficult to achieve good classification accuracy for each class in case of imbalanced data sets. This problem arises in many real world applications like medical diagnosis of rare medical disease, fraud detection in financial domain, and faulty area detection in network troubleshooting etc. The imbalanced data set consists of small number of instances of minority classes and large number of instances of majority classes. Overall classification accuracy is computed by taking the ratio of correctly classified instances to total number of instances in a data set. For imbalanced data sets, correct classification of minority class instances contribute minimum in improvement of overall classification accuracy as compared to classification of majority class instances. Conventional classification techniques like Artificial Neural Network (ANN), Support Vector Machine (SVM), and Naïve Bayes (NB) consider overall classification accuracy of the classifier only and thus evolve biased classifiers in case of imbalanced data set. However, instances of minority classes may contain rare but important information in many real world data sets. Thus, a classification technique that provides good classification accuracy on both minority and majority classes is needed. This paper proposes a combination of Multi Objective Genetic Programming (MOGP) and probability based Gaussian classifier for classification of imbalanced data set. MOGP considers classification accuracy of each class as separate objective and not the overall accuracy as single objective. Gaussian classifier is generative classifier in which distribution of one class never affect the classification of instances of other classes. The proposed methodology is applied on classification of imbalanced data sets from medical, life science, automobile, and space science domain. The results suggest that MOGP classifier outperformed other conventional classifiers (ANN, SVM, and NB) on tested imbalanced data sets.

One of the more prevalent problems when working with bioinformatics datasets is class imbalance, when there are more instances in one class compared to the other class (es). This problem is made worse because frequently, the class of interest is also the minority class. A possible solution is data sampling, a powerful tool for combating class imbalance by adding or removing instances to make the dataset more balanced. In addition to the choice of including data sampling, one of the most important decisions when applying data is what the final class ratio should be. Commonly, the final class ratio when data is applied is 50:50, however it is an open question whether other ratios are more appropriate for certain imbalanced datasets (all datasets in this paper have 25.16% minority instances or less) where a 50:50 ratio requires extreme modification to the dataset. In this work we compare six different data approaches (feature selection with the pair wise combinations of three data techniques and two final class ratios) with feature selection without data with the goal of determining if the inclusion of data is beneficial and if so, what should be the final class ratio. In order to test the six data approaches and feature selection alone thoroughly, we utilize seven imbalanced and high-dimensional datasets, three feature selection techniques, and six classifiers. Our results show that for a majority of scenarios, random under along with either 35:65 or 50:50 is the best data approach. Statistical analysis shows that there is significant difference between the data approaches. However, despite this, we still recommend using random under along with 35:65 as the final class ratio. This is because of the frequency of both random under and 35:65 being the most frequent top performing data technique and class ratio respectively. Additionally, 35:65 will have fewer negative impacts than 50:50 (less data loss or over fitting, which makes it a better choice if all other factors are equal) and random under is more computationally efficient than any other form of sampling, including no sampling (both by not requiring any internal calculations and by producing a reduced, easier-to-work-with dataset). To our knowledge, this is the most comprehensive work which focuses on the choice of the inclusion and implementation of data with different final class ratios on bioinformatics datasets which exhibit such large levels of class imbalance.

Medical diagnosis is a crucial step for patient treatment. However, diagnosis is prone to bias due to imbalanced datasets. To overcome the imbalanced dataset problem, simple minority oversampling technique (SMOTE) was proposed that can generate new synthetic samples at data level to create the balance between minority and majority classes. However, the synthetic samples are generated on a random basis which causes class mixture problem; thus, resulting in deteriorating the classification performance and biased diagnosis. In order to overcome the SMOTE shortcomings, some modified methods were proposed that try to generate synthetic samples along the line segment of selected minority samples. Most of these methods adopt one of the two policies for selecting minority samples to generate synthetic samples: borderline region sampling or safe region sampling. However, they both suffer from over-generalisation problem. We propose a modified SMOTE-based resampling method called RSMOTE to alleviate the medical imbalanced dataset problem. We provide an in-depth analysis and verify the performance of RSMOTE over imbalanced medical datasets. In this paper, the proposed RSMOTE divides the minority sample domain into four regions (normal, semi-normal, semi-critical, and critical) based on the minority sample density analysis. RSMOTE discovers the minority sample region globally and applies the resampling near a specific group of samples. Our analysis and experiments verify that if synthetic samples are generated in the regions with high minority sample density, classification performance will be improved due to low risk of class mixture. Unlike some safe region methods, RSMOTE decides the region of minority samples on a global basis, thus removing the over-generalisation problem. Classic and additional evaluation metrics are considered to measure the effectiveness of the modified method: Recall, FP Rate, Precision, F-Measure, ROC area, and Average Aggregated Metric. We carried out experiments over various imbalanced medical datasets. Based on the minority sample density analysis, we propose RSMOTE method that divides the minority sample domain into four regions. The proposed RSMOTE includes four re-sampling methods that each of them carries out resampling on a specific region. According to the experimental results, resampling on the regions with high minority sample density obtained better results while those with lower minority sample density got the inferior results. Thus, we conclude that the RSMOTE is a more flexible resampling method for the imbalanced medical datasets that is capable of generating samples with various minority sample densities.

The challenges related to handling of the gigantic imbalanced data volumes are incredible and has set a new trail for its efficient processing. The inventive prospects contained by these huge imbalanced data sets have posed a priority of concern in recent research avenues. The several applications handling imbalanced Big Data sets have noted significance for precise classification while determining unidentified values from these data sets. Traditional classifiers are not able to discourse the imbalance of class distribution among the data samples. A class having fewer samples indicates difficulty in learning, whereas it points to a notable drop in the performance. Recent studies demonstrate that the classifier independent set of oversampling techniques are more capable to efficiently handle the issues raised in imbalanced data sets. An enhanced oversampling technique, viz., Minority–Majority Mix mean Oversampling Technique (MMMmOT), improving classification performance is discussed in detail in this paper. An appropriate consideration of majority as well as minority samples is planned to generate the synthetic samples. The proposed technique is investigated encircling data sets mainly from the UCI repository over Apache Hadoop. Furthermore, the stimulus of maintaining the imbalance ratio with better oversampling instances from the generated pool is analyzed. The results of classification performance are recognized using standard parameters like F-Measure and area under the curve. The achieved experimental outcomes clearly exhibit the preeminence of the presented technique over the traditional techniques.

The imbalanced dataset is a challenging issue in many classification tasks. Because it leads a machine learning algorithm to poor generalization and performance. The imbalanced dataset is characterized as having a huge difference between the number of samples that contain each class. Unfortunately, various resampling methods are proposed to solve this problem. In our work, we target enhancing the handling of the imbalanced dataset using a new oversampling technique based on generative adversarial neural networks. Our method is benchmarked against the widely used oversampling technique including the synthetic minority oversampling technique (SMOTE), random oversampling technique (ROS), and the adaptive synthetic sampling approach(ADSYN). Additionally, three machine learning algorithms are used for evaluation. The outcome of our experiments on a real-world credit card dataset shows the strong ability of the proposed solution against the competitive oversampling techniques to overcome the imbalanced problem in the European credit card dataset.

The problem of class imbalance in machine learning occurs when there is a relatively big disproportional distribution of classes in the data for classification tasks. In many real-world domains, such as in healthcare, finance, and predictive maintenance, the number of data points of a less important class (usually the negative class) is much higher than the class of greater interest (usually the positive or target class). This affects the ability of many learning algorithms to find good classification models. To address that, many approaches for solving this problem have been proposed, prominently including ensemble methods integrated with sampling-based techniques. However, these methods are still prone to the negative effects of sampling-based techniques that alter class distributions via over-sampling or under-sampling, which can lead to overfitting or discarding useful data, respectively, and thus affect performance. In this paper, we propose a new data preprocessing sampling technique dubbed as (sBal) for ensemble methods for binary classification in the case of imbalanced datasets. Our proposed method first turns the imbalanced dataset into several balanced bins/bags. Then multiple base learners are induced on the balanced bags and finally, the classification results are combined using a specific ensemble rule. We evaluated the performance of our proposed method on 50 imbalanced real-world binary datasets and compared its performance with well-known ensemble methods that utilize data preprocessing techniques namely SMOTEBagging, SMOTEBoost, RUSBoost, and RAMOBoost. The results reveal that the proposed method brings considerable improvement in classification performance relevant to the compared methods. We performed statistical significance analysis using Friedman’s non-parametric statistical test with Bergman post-hoc test. The analysis showed that our method performed significantly better than the majority of the methods across many datasets, suggesting a better preprocessing approach than the ones used in compared methods. We also highlight possible extensions to the method that can improve its effectiveness.KeywordsData samplingEnsemble methodsImbalanced datasetsSplit balancingRAMOBoostSMOTEBaggingSMOTEBoost

The majority of machine learning algorithms previously designed usually assume that their training sets are well-balanced, but data in the real-world is usually imbalanced. The class imbalance problem is pervasive and ubiquitous, causing trouble to a large segment of the data mining community. As the conventional machine learning algorithms have bad performance when they learn from imbalanced data sets, it is necessary to find solutions to machine learning on imbalanced data sets. This paper presents a novel Isomap-based hybrid re-sampling approach to improve the conventional SMOTE algorithm by incorporating the Isometric feature mapping algorithm (Isomap). Experiment results demonstrate that this hybrid re-sampling algorithm attains a performance superior to that of the re-sampling. It is clear that the Isomap method is an effective means to reduce the dimension of the re-sampling. This provides a new possible solution for dealing with the IDS classification.

The problem of classification for imbalanced datasets is frequently encountered in practical applications. The data to be classified in this problem are skewed, i.e., the samples of one class (the minority class) are much less than those of other classes (the majority class). When dealing with imbalanced datasets, most classifiers encounter a common limitation, that is, they often obtain better classification performances on the majority classes than those on the minority class. To alleviate the limitation, in this study, a fuzzy rule-based modeling approach using information granules is proposed. Information granules, as some entities derived and abstracted from data, can be used to describe and capture the characteristics (distribution and structure) of data from both majority and minority classes. Since the geometric characteristics of information granules depend on the distance measures used in the granulation process, the main idea of this study is to construct information granules on each class of imbalanced data using Minkowski distance measures and then to establish the classification models by using “If-Then” rules. The experimental results involving synthetic and publicly available datasets reflect that the proposed Minkowski distance-based method can produce information granules with a series of geometric shapes and construct granular models with satisfying classification performance for imbalanced datasets.

Deep learning models often exhibit bias when trained on imbalanced datasets, tending to favor majority classes. While Deep Synthetic Minority Over-sampling Technique (DeepSMOTE) mitigates this challenge by generating synthetic minority class images within an autoencoder’s latent space, the proposed architecture achieves further performance enhancement through the optimization of the latent space structure. This strategy introduces a composite loss function that minimizes intra-class distances while maximizing inter-class distances by incorporating class centroid information into the autoencoder training process. The approach was evaluated on six benchmark image datasets (MNIST, Fashion-MNIST, EMNIST, SVHN, GTSRB, and CIFAR10) with severe class imbalance ratios of 750:1, using five-fold cross-validation. Results demonstrate that Deep Class-Latent Synthetic Minority Oversampling Technique (DeepCLSMOTE) consistently outperforms baseline methods, including Balancing Generative Adversarial Network (BAGAN) and DeepSMOTE across all evaluation metrics, achieving statistically significant improvements in macro-average accuracy, precision, recall, and F1-measure. The enhanced performance is attributed to improved discriminative feature extraction in the optimized latent space, resulting in superior classification performance on highly imbalanced image datasets, particularly for critical minority classes.

One of the main drawbacks of boosting is its overfitting and poor predictive accuracy when the training dataset is small and imbalanced. In this paper, we introduce a novel learning algorithm Boost-BFKO, which combines boosting and data generation. It is suitable for small and imbalanced training datasets. To enlarge training sets, Boost-BFKO uses the adaptive Balanced Feature Knockout procedure (BFKO) to generate new synthetic samples. To enrich the training sets, Boost-BFKO selects seed samples from the minority class, and rebalances the total weights of the different classes in the updated training dataset. Experiments on Caltech 101 database showed that our method achieves a desirable performance when only a few training samples are available for binary classification and multiple object classification.

A synthetic informative minority over-sampling (SIMO) algorithm leveraging support vector machine to enhance learning from imbalanced datasets