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Synthetic Data Simulation and Model Evaluation for Advanced Financial Fraud Detection Systems Using Matlab

Author : Waqas Javaid

Abstract

This study presents a comprehensive, simulation-based framework for credit card fraud detection, addressing the critical challenges of severe class imbalance and asymmetric misclassification costs. We generate realistic synthetic transaction data exhibiting natural fraud patterns and employ a multi-model ensemble approach, evaluating Logistic Regression, Support Vector Machine (RBF kernel), Random Forest, Gradient Boosting, and an Autoencoder for anomaly detection [1]. A custom cost matrix prioritizes the detection of fraudulent transactions over false alarms. Performance is rigorously benchmarked using ROC-AUC, precision-recall curves, and confusion matrices [2]. Results demonstrate that ensemble methods, particularly Random Forest and Gradient Boosting, achieve superior discriminative power, while the autoencoder provides complementary unsupervised insights [3]. The framework offers a robust, reproducible pipeline for developing and benchmarking cost-sensitive fraud detection systems, balancing predictive accuracy with operational economic constraints.

  1. Introduction

The proliferation of digital transactions has rendered credit card fraud a persistent and evolving threat to global financial ecosystems, incurring annual losses amounting to billions of dollars [4].

Figure 1: Advanced Machine Learning–Based Credit Card Fraud Detection Framework

This malicious activity not only inflicts direct financial damage but also erodes consumer trust and imposes significant operational burdens on financial institutions. The core technical challenge in automating its detection lies in the profound class imbalance, where fraudulent transactions constitute a minute fraction of total activity, often less than 1%. This rarity complicates model training and necessitates specialized evaluation metrics beyond simple accuracy. Furthermore, the cost of errors is highly asymmetric; failing to identify a fraudulent transaction (a false negative) is typically orders of magnitude more detrimental than flagging a legitimate one for review (a false positive). Consequently, effective systems must be explicitly designed to be cost-sensitive, prioritizing recall while maintaining manageable precision [5].

Table 1: Machine Learning Models Employed for Fraud Detection

ModelObjectiveLearning Type
Logistic RegressionBaseline fraud classificationSupervised
Support Vector Machine (RBF)Nonlinear decision boundary modelingSupervised
Random ForestEnsemble-based fraud detectionSupervised
Gradient BoostingBoosted tree-based classificationSupervised

Traditional machine learning models, when applied naively to such imbalanced datasets, tend to be biased toward the majority class, rendering them ineffective [6]. This study addresses these multifaceted challenges by constructing a sophisticated, simulation-based framework. We generate a realistic, imbalanced synthetic dataset that mirrors key fraud indicators, enabling controlled experimentation and benchmarking. The framework implements and critically compares a diverse suite of five state-of-the-art detection paradigms from interpretable logistic regression and kernel-based support vector machines to powerful ensemble methods like Random Forest and Gradient Boosting, alongside an unsupervised deep learning autoencoder for anomaly detection. Each model is evaluated under a realistic cost matrix, with performance assessed through AUC-ROC curves, precision-recall analysis, and detailed confusion matrices [7]. This systematic approach provides a robust foundation for developing high-stakes financial monitoring systems that must navigate the delicate trade-off between security, customer experience, and economic viability [8].

1.1 The Global Challenge of Credit Card Fraud

Credit card fraud represents a critical and escalating threat within the modern digital economy, undermining the security of financial systems worldwide. As electronic transactions become ubiquitous, malicious actors continuously develop sophisticated techniques to exploit vulnerabilities, leading to substantial annual financial losses for institutions and consumers alike. This criminal activity extends beyond immediate monetary damage, eroding the foundational trust required for e-commerce to function and imposing heavy costs related to fraud investigation, customer service, and regulatory compliance [9]. The dynamic and adaptive nature of fraud schemes means that static, rule-based detection systems are rapidly rendered obsolete. Consequently, there is an urgent and pressing need for intelligent, adaptive, and highly accurate automated systems capable of identifying fraudulent transactions in real-time. The development of such systems is not merely a technical exercise but a vital component of financial infrastructure resilience. This paper addresses this imperative by developing a comprehensive machine learning framework, recognizing that effective fraud detection is a cornerstone of cybersecurity in the financial sector [10]. The challenge is formidable, requiring models that can learn subtle, non-linear patterns from data while operating under stringent constraints.

1.2 The Technical Hurdle of Severe Class Imbalance

The primary technical obstacle in building effective fraud detection models is the extreme class imbalance inherent in transaction datasets. In a typical operational environment, over 99% of transactions are legitimate, while fraudulent cases constitute a tiny, often less than 1%, minority class. This severe skew presents a fundamental problem for standard machine learning algorithms, which are designed to maximize overall accuracy [11]. A naive model could achieve over 99% accuracy by simply predicting every transaction as legitimate, yet it would be completely useless by failing to catch any fraud. This imbalance biases the learning process, causing models to overlook the nuanced patterns that characterize fraudulent activity. Training on such data requires specialized sampling techniques, algorithmic adjustments, and, most critically, evaluation metrics that are sensitive to minority class performance. Metrics like precision, recall, and the area under the Precision-Recall curve become far more informative than simple accuracy [12]. Our methodology confronts this imbalance directly, both in the construction of our synthetic dataset and in the design of our model evaluation protocol, ensuring that our analyses reflect the practical realities of the problem domain rather than abstract statistical performance.

1.3 The Critical Need for Cost-Sensitive Learning

Beyond statistical imbalance, fraud detection is fundamentally a cost-sensitive optimization problem where different types of errors have dramatically different consequences. The cost of a false negative failing to detect an actual fraudulent transaction can include the entire value of the transaction, associated fees, and long-term customer churn. Conversely, a false positive incorrectly flagging a legitimate transaction typically incurs a much lower cost, such as a customer service inquiry or a temporary inconvenience for the cardholder [13]. This asymmetry must be explicitly encoded into the learning process; a model optimized for balanced error rates will be economically suboptimal. Our framework integrates this reality by employing a custom cost matrix during the training of specific models, like the Support Vector Machine, and by prioritizing metrics that reflect this trade-off. We shift the optimization goal from pure predictive accuracy to minimizing the total expected financial cost [14]. This cost-aware approach is essential for transitioning an academically interesting model into a deployable system that aligns with the business objectives and risk tolerance of a financial institution.

1.4 Limitations of Single-Model Approaches and the Promise of Hybrid Frameworks

Relying on a single machine learning paradigm for fraud detection is often insufficient due to the diverse and evolving nature of fraud patterns. Traditional models like Logistic Regression offer interpretability but may lack the complexity to capture intricate non-linear relationships. Ensemble methods like Random Forest improve performance but can be computationally expensive. Unsupervised anomaly detection methods, such as autoencoders, can identify novel fraud schemes without labeled data but may suffer from high false positive rates. Therefore, a robust defense strategy necessitates a multi-pronged, hybrid approach [15]. This study advocates for and implements a comprehensive framework that benchmarks and combines the strengths of various methodologies. We systematically evaluate five distinct model families generalized linear models, kernel methods, bagging ensembles, boosting ensembles, and deep learning-based anomaly detection within a unified pipeline. This comparative analysis allows us to identify the most suitable model for different operational priorities, whether that be inference speed, interpretability, or pure detection performance, and lays the groundwork for future ensemble or meta-classifier systems.

1.5 The Role of Feature Engineering and Realistic Data Simulation

A critical yet often underestimated component of effective fraud detection lies in constructing meaningful features that capture fraudulent behavior. Raw transaction logs are insufficient; domain knowledge must be translated into predictive variables. Our synthetic data generation process meticulously engineers nine distinct features that mirror real-world fraud indicators. These include not only basic attributes like transaction amount and time but also sophisticated behavioral markers such as geographic velocity (the speed of transaction location changes) and device risk scores [16]. By programmatically injecting fraud patterns into these features for instance, increasing transaction amounts and geographic velocity for fraudulent cases we create a dataset where fraud has a discernible but subtle signature. This approach ensures our models learn from realistic signals rather than artificial separability [17]. The feature correlation heatmap included in our analysis further validates the relationships between engineered features, demonstrating how multi-dimensional patterns must be interpreted collectively rather than in isolation for accurate detection.

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1.6 Model Interpretability and Operational Deployment Considerations

While predictive performance is paramount, the practical deployment of a fraud detection system requires model interpretability and operational efficiency. Financial institutions and regulators increasingly demand explanations for why a transaction was flagged, necessitating models that provide some degree of transparency. Among our tested models, Logistic Regression offers direct coefficient interpretation, while Random Forest can provide feature importance rankings, both valuable for investigators. Conversely, the Autoencoder and complex ensembles act more as “black boxes.” Furthermore, operational constraints such as real-time inference latency, computational resource requirements, and model update frequency are critical. Our benchmarking framework, while focused on offline performance, establishes a foundation for these considerations by comparing model complexity and training time [18]. The choice between the high-performing Gradient Boosting model and the faster-to-train Random Forest, for example, represents a classic trade-off between precision and operational agility that must be resolved based on specific infrastructure and volume requirements.

1.7 Addressing Concept Drift and Model Maintenance in Production

A fundamental challenge not addressed in static datasets is concept drift the phenomenon where the statistical properties of fraudulent behavior change over time, causing model performance to degrade. Fraudsters adapt their tactics, and legitimate customer behavior evolves, meaning a model trained on today’s data may be ineffective tomorrow. Our framework, though static, provides the modular infrastructure necessary for continuous learning. The synthetic data pipeline can be extended to simulate temporal drift, and the ensemble of models can be retrained on sliding windows of recent data [19]. The Autoencoder, in particular, is well-suited for identifying novel, previously unseen fraud patterns (zero-day fraud) that deviate from normal behavior, serving as an early warning system for concept drift. Future iterations of this system would require a robust monitoring layer to track performance metrics like precision-recall in real-time and trigger automatic retraining when drift is detected, ensuring the system remains adaptive and resilient in a dynamic threat landscape.

1.8 Ethical and Privacy Implications in Fraud Detection Systems

The development of high-surveillance financial monitoring systems raises significant ethical and privacy concerns that must be proactively addressed. A system that inaccurately flags transactions can unfairly penalize legitimate customers, potentially leading to denied transactions, frozen accounts, and reputational harm disproportionately affecting certain demographic groups if biases exist in the training data.

Table 2: Description of Synthetic Credit Card Transaction Dataset

FeatureDescriptionData Type
AmountTransaction monetary valueContinuous
TimeOfDayTime of transaction (0–24 hours)Continuous
MerchantRiskMerchant risk indexContinuous
GeoVelocityGeographical transaction velocityContinuous
DeviceRiskDevice fingerprint risk scoreContinuous
PastFraudsNumber of past fraud incidentsDiscrete
TxnFrequencyTransaction frequencyContinuous
AccountAgeCustomer account age (years)Continuous
InternationalInternational transaction indicatorBinary

Use of synthetic data mitigates privacy risks associated with real customer information, but a production system must comply with regulations like GDPR, requiring explainable decisions and mechanisms for customer recourse [20]. The cost matrix we implement is a first step toward formalizing a risk-ethical trade-off, explicitly deciding how many false alarms are acceptable to catch a fraud. Future work must integrate fairness audits to detect and correct for algorithmic bias across sensitive attributes and develop transparent dispute resolution protocols, ensuring that the pursuit of security does not come at the cost of equity and consumer rights.

1.9 Future Research Directions

This comprehensive pipeline opens several avenues for future research. Immediate extensions include implementing more advanced deep learning architectures like Long Short-Term Memory (LSTM) networks to model sequences of user transactions for behavioral profiling, and graph neural networks to analyze networks of connected accounts and merchants. Furthermore, exploring hybrid models that combine the supervised ensemble scores with unsupervised anomaly scores into a meta-classifier could yield performance gains. Another critical direction is federated learning, allowing models to be trained across multiple financial institutions without sharing sensitive raw data, thereby improving generalization while preserving privacy [21]. In conclusion, our work demonstrates that effective credit card fraud detection is a multi-dimensional problem requiring a blend of realistic data simulation, cost-sensitive multi-model benchmarking, and ongoing consideration of operational, adaptive, and ethical constraints. The provided framework serves as a robust foundation for both academic research and the development of next-generation, responsible, and resilient financial security systems.

  1. Problem Statement

The core problem addressed is the inadequacy of standard machine learning approaches to autonomously detect credit card fraud within highly imbalanced, real-time transaction streams where fraudulent activities are rare but economically devastating. Existing systems often fail to balance the asymmetric cost of errors, prioritizing general accuracy over the critical need to minimize false negatives, thus allowing substantial financial leakage. Furthermore, the lack of accessible, realistic benchmarking frameworks using synthetic data hampers reproducible research and rapid prototyping of cost-sensitive models. There is a pronounced gap in holistic pipelines that integrate traditional supervised classifiers with unsupervised anomaly detection to identify both known and novel fraud patterns. Consequently, financial institutions require a robust, scalable, and ethically considerate methodology that simultaneously optimizes for high detection recall, manageable operational precision, interpretability for regulatory compliance, and adaptability to evolving fraudulent tactics, all while operating under stringent computational and privacy constraints.

  1. Mathematical Approach

The mathematical framework formulates fraud detection as a cost-sensitive binary classification problem, minimizing the expected risk:

Where (C) is an asymmetric cost matrix penalizing false negatives severely. It employs maximum likelihood estimation for logistic regression, structural risk minimization with kernel tricks for SVM, and ensemble methods that aggregate decision trees via bootstrap aggregation (Random Forest) or sequential error correction (Gradient Boosting). Anomaly detection is modeled through an autoencoder neural network that learns a compressed representation and minimizes the reconstruction error:

Where high error indicates outliers. Model performance is evaluated via area under the ROC curve (AUC-ROC) and precision-recall metrics, optimizing the probability threshold to satisfy the operational cost constraint:

The mathematical approach begins by framing the problem as one of expected risk minimization, where the goal is to reduce the total financial cost of prediction errors. This is governed by a custom matrix that assigns a much heavier penalty to missing a fraudulent transaction compared to incorrectly flagging a legitimate one. For the core classifiers, different principles are applied: one model finds the optimal linear boundary by maximizing the likelihood of the observed data, another creates a complex non-linear boundary by maximizing the margin between classes in a high-dimensional space. The ensemble methods combine many simple decision trees, either by averaging independent models built on random data subsets or by sequentially building new models that focus on correcting the errors of the previous ones. Separately, the anomaly detection model works by learning to compress and then reconstruct normal transaction data; transactions that are poorly reconstructed are deemed anomalous, with their anomaly score measured by the average squared reconstruction error. Finally, model selection is not based on simple accuracy but on the area under the receiver operating characteristic curve and the precision-recall relationship, with the final decision threshold tuned to balance the predefined financial costs of false alarms and missed fraud.

  1. Methodology

The methodology is structured as a complete, reproducible pipeline for developing and benchmarking fraud detection systems. It commences with the generation of a realistic synthetic dataset of fifteen thousand transactions, featuring a deliberate two percent fraud rate to simulate severe class imbalance. Nine explanatory features are engineered, including transaction amount, time, merchant risk, geographic velocity, and behavioral markers, with systematic pattern injections such as inflated amounts and velocity to create discernible fraud signatures within the minority class [22]. All features are standardized to zero mean and unit variance to ensure model stability. The data is then partitioned into distinct training and testing sets using a seventy-thirty holdout strategy. A foundational cost matrix is defined, assigning a penalty twenty times greater for missing fraud than for a false alert, explicitly encoding the business asymmetry into the learning process. Five distinct model architectures are implemented and trained: a Logistic Regression model as a linear baseline; a non-linear Support Vector Machine with a Radial Basis Function kernel, trained with the cost matrix; a robust Random Forest ensemble of three hundred decision trees; a Gradient Boosting model using LogitBoost over three hundred and fifty cycles; and a deep learning Autoencoder with six neurons in its bottleneck layer, trained exclusively on legitimate transactions to learn normative patterns. Each model produces a continuous fraud propensity or anomaly score for the test set [23]. Performance is rigorously evaluated using the area under the Receiver Operating Characteristic curve for each model, providing a threshold-invariant measure of discriminative power. A detailed Precision-Recall curve is analyzed for the top-performing model to examine the trade-off at various operational points. Predictions from the Random Forest are dichotomized at a threshold of zero point five to generate a confusion matrix for interpretable error analysis. Finally, the distribution of the Autoencoder’s reconstruction error scores is compared between legitimate and fraudulent transactions to assess its unsupervised anomaly detection capability [24]. The entire process is supported by six diagnostic visualizations that offer comprehensive insight into data characteristics and model behavior.

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  1. Design Matlab Simulation and Analysis

The simulation constructs a controlled, synthetic environment to rigorously benchmark fraud detection algorithms under realistic but perfectly known conditions. It begins by generating a dataset of fifteen thousand financial transactions, deliberately crafted to reflect the severe class imbalance of real-world systems with a fraud rate of two percent. Nine distinct features are synthesized, ranging from basic transaction attributes like amount and time to sophisticated behavioral risk scores such as geographic velocity and merchant risk, using statistical distributions to emulate natural variation. The core fraud signature is programmatically injected by selectively modifying the feature values for the fraud subset: transaction amounts are quadrupled, geographic velocity is tripled, and risk scores are substantially increased to create a detectable but non-obvious pattern. All features are then standardized to ensure model stability and comparability. The data is split into training and testing partitions using a standard holdout method. A critical component is the explicit definition of an asymmetric cost matrix, which assigns a penalty twenty times greater for missing a fraud than for a false alert, thereby embedding the business logic directly into the learning objective. Five diverse models a linear Logistic Regression, a non-linear Support Vector Machine with a Radial Basis Function kernel, a robust Random Forest ensemble, a sequential Gradient Boosting model, and a deep learning Autoencoder are trained and evaluated on this common ground. Their performance is quantified using the area under the Receiver Operating Characteristic curve, providing a threshold-independent measure of discriminative power. The simulation culminates in a suite of six diagnostic visualizations that reveal the class distribution, feature correlations, comparative model performance via ROC curves, the precision-recall trade-off for the best model, a detailed confusion matrix, and the anomaly score distribution from the unsupervised autoencoder, offering a complete and reproducible analytical narrative of the detection problem.

Figure 2: Pie chart showing the extreme class imbalance between legitimate (98%) and fraudulent (2%) transactions in the synthetic dataset.

This figure visually quantifies the fundamental challenge of credit card fraud detection: extreme class imbalance. The pie chart clearly demonstrates that fraudulent transactions constitute only a tiny minority (2%) of all transactions, while legitimate transactions dominate the dataset (98%). This imbalance creates significant difficulties for machine learning algorithms, as models tend to be biased toward the majority class. Understanding this distribution is crucial for selecting appropriate evaluation metrics and sampling strategies. The visualization emphasizes why accuracy alone is a misleading performance measure, since a naive classifier predicting all transactions as legitimate would achieve 98% accuracy while failing completely at its primary task. This distribution directly motivates the need for specialized techniques like cost-sensitive learning and anomaly detection approaches.

Figure 3: Heatmap visualizing the pairwise linear correlation matrix between the nine engineered features after z-score normalization.

This heatmap provides insight into the underlying structure and relationships within the feature space. Each cell represents the Pearson correlation coefficient between two features, with colors indicating strength and direction of linear relationships (blue for positive, red for negative). The visualization helps identify potential multicollinearity issues where highly correlated features might provide redundant information to the models. Features like transaction frequency and geographic velocity show moderate positive correlation with fraud indicators, while account age exhibits negative correlations with risk-related features. This analysis validates the feature engineering process and informs model selection decisions, particularly for linear models that assume feature independence. The diagonal shows perfect self-correlation as expected.

Figure 4: Receiver Operating Characteristic (ROC) curves comparing the performance of all five models (LR, SVM, RF, GBT, AE) for fraud detection.

This comprehensive comparison plots the true positive rate against the false positive rate across all possible classification thresholds for each model. The curves demonstrate the trade-off between sensitivity (recall) and specificity, with models closer to the top-left corner performing better. The area under each curve (AUC) provides a single metric for model comparison, where 1.0 represents perfect discrimination and 0.5 represents random guessing. The ensemble methods (Random Forest and Gradient Boosting) consistently achieve the highest AUC values, indicating superior overall discriminative power. The visualization enables informed threshold selection based on operational requirements, whether prioritizing high recall (lower threshold) or high precision (higher threshold).

Figure 5: Precision-Recall curve for the Random Forest model, illustrating the trade-off between precision and recall across different classification thresholds.

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his curve is particularly informative for imbalanced classification problems where the positive class (fraud) is rare. Unlike ROC curves, Precision-Recall curves are sensitive to class imbalance and provide a more realistic assessment of model performance for the minority class. The curve shows how precision decreases as recall increases, highlighting the operational trade-off: capturing more fraud cases (high recall) comes at the cost of more false alarms (lower precision). The area under this curve (AUPRC) serves as a key performance metric, with higher values indicating better ability to maintain high precision while achieving high recall. This visualization helps determine the optimal operating point based on business constraints and cost considerations.

Figure 6: Confusion matrix for the Random Forest model at a 0.5 decision threshold, displaying counts of true positives, false positives, true negatives, and false negatives.

This matrix provides an intuitive breakdown of classification results, showing exactly where the model succeeds and fails. The four quadrants represent: correctly identified legitimate transactions (true negatives), correctly detected fraud cases (true positives), legitimate transactions incorrectly flagged as fraud (false positives), and missed fraud cases (false negatives). The visualization quantifies the real-world impact of the model’s decisions, with particular attention to the false negatives due to their high financial cost. The matrix enables calculation of key metrics like precision, recall, and F1-score, and supports error analysis to identify patterns in misclassified transactions. The color intensity helps quickly assess model performance.

Figure 7: Histogram distributions of Autoencoder anomaly scores (normalized reconstruction error) for legitimate versus fraudulent test transactions.

This figure demonstrates the effectiveness of unsupervised anomaly detection by visualizing how well the autoencoder separates normal from anomalous patterns. The reconstruction error represents how much a transaction deviates from learned normal behavior, with higher scores indicating greater anomaly. The overlapping distributions show that while most fraudulent transactions have higher reconstruction errors, there’s significant overlap with legitimate transactions, explaining the autoencoder’s moderate AUC performance. The visualization reveals that the autoencoder successfully identifies many fraud cases as outliers but cannot perfectly separate the classes without supervision. This approach is particularly valuable for detecting novel fraud patterns not present in the training data, complementing supervised methods.

Figure 8: Neural Network Training Explanation

The autoencoder neural network is trained as an unsupervised anomaly detector through a specialized process focused on learning normal transaction patterns. Unlike supervised models that learn from labeled fraud cases, the autoencoder is trained exclusively on legitimate transaction data, allowing it to encode and reconstruct the statistical distribution of normal behavior. The network architecture consists of symmetric encoder and decoder components with a compressed bottleneck layer containing only six neurons, which forces the network to learn a compact, efficient representation of the input data. During training over two hundred and fifty epochs, the network minimizes the mean squared error reconstruction loss between input transactions and their reconstructed outputs, while regularization techniques including L2 weight decay and sparsity constraints prevent overfitting and encourage the learning of robust features. The training process implements backpropagation with optimization algorithms to adjust connection weights, gradually improving the network’s ability to accurately reconstruct normal patterns while becoming sensitive to deviations. Once trained, the autoencoder’s reconstruction error serves as an anomaly score, where transactions that significantly deviate from learned normal patterns such as fraudulent activities with unusual feature combinations produce high reconstruction errors and are flagged as potential fraud, enabling detection of novel attack patterns without requiring labeled fraud examples in training.

  1. Results and Discussion

The results demonstrate that ensemble methods consistently outperform other approaches in distinguishing fraudulent transactions, with Random Forest achieving the highest AUC of 0.963 and Gradient Boosting closely following at 0.957, validating their robustness in handling complex, non-linear patterns within imbalanced data. The Support Vector Machine with RBF kernel attained a competitive AUC of 0.924, though its performance was sensitive to the cost matrix and kernel parameter tuning, while Logistic Regression, as expected, provided a respectable linear baseline with an AUC of 0.851. Interestingly, the unsupervised Autoencoder achieved a notable AUC of 0.812 solely through anomaly detection, confirming that fraudulent transactions exhibit fundamentally different reconstruction characteristics despite no explicit fraud labels during its training. The Precision-Recall curve for Random Forest reveals a critical trade-off: at an 80% recall threshold, precision remains above 70%, indicating that operational deployment would require accepting approximately three false alarms for every ten alerts to capture eight out of ten fraud cases a business decision informed by the asymmetric cost matrix [25]. The confusion matrix at the default 0.5 threshold shows that Random Forest correctly identified 92% of fraud cases while maintaining a false positive rate below 5%, suggesting effective discrimination but highlighting room for threshold optimization based on specific cost constraints. The Autoencoder’s anomaly score distribution displayed partial but significant separation between classes, with a heavier right-tailed distribution for fraud cases, explaining its moderate performance and suggesting its value as a complementary detector for novel fraud schemes [26]. These findings collectively indicate that while ensemble methods provide superior overall performance, a hybrid system combining supervised Random Forest predictions with Autoencoder anomaly scores could yield enhanced detection capabilities, particularly for emerging fraud patterns. The results underscore the necessity of cost-sensitive evaluation, as optimizing for AUC alone does not guarantee optimal economic outcomes given the twenty-to-one cost asymmetry between error types. Future work should investigate dynamic threshold adjustment mechanisms and model ensembling strategies to further reduce false negatives without proportionally increasing operational costs from false positives [27].

  1. Conclusion

This study successfully developed and validated a comprehensive, simulation-based framework for benchmarking credit card fraud detection systems under realistic conditions of severe class imbalance and asymmetric error costs [28]. The results demonstrate that ensemble methods, particularly Random Forest and Gradient Boosting, achieve superior discriminative performance for this task, while unsupervised autoencoders provide valuable complementary capability for identifying anomalous patterns. The explicit integration of a cost matrix ensures models are optimized for economic impact rather than abstract statistical metrics [29]. The end-to-end pipeline from synthetic data generation to multi-faceted evaluation provides a reproducible methodological standard for future research. Ultimately, this work confirms that effective fraud detection requires a hybrid, cost-aware strategy combining supervised learning’s precision with anomaly detection’s adaptability, forming a critical foundation for building resilient and economically viable financial security systems [30].

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