Categorical Attributes Research Articles

A fair-multicluster approach to clustering of categorical data

In the last few years, the need of preventing classification biases due to race, gender, social status, etc. has increased the interest in designing fair clustering algorithms. The main idea is to ensure that the output of a cluster algorithm is not biased towards or against specific subgroups of the population. There is a growing specialized literature on this topic, dealing with the problem of clustering numerical data bases. Nevertheless, to our knowledge, there are no previous papers devoted to the problem of fair clustering of pure categorical attributes. In this paper, we show that the Multicluster methodology proposed by Santos and Heras (Interdiscip J Inf Knowl Manag 15:227–246, 2020. https://doi.org/10.28945/4643) for clustering categorical data, can be modified in order to increase the fairness of the clusters. Of course, there is a trade-off between fairness and efficiency, so that an increase in the fairness objective usually leads to a loss of classification efficiency. Yet it is possible to reach a reasonable compromise between these goals, since the methodology proposed by Santos and Heras (2020) can be easily adapted in order to get homogeneous and fair clusters.

High-Cardinality Categorical Attributes and Credit Card Fraud Detection

Credit card transactions may contain some categorical attributes with large domains, involving up to hundreds of possible values, also known as high-cardinality attributes. The inclusion of such attributes makes analysis harder, due to results with poorer generalization and higher resource usage. A common practice is, therefore, to ignore such attributes, removing them, albeit wasting the information they provided. Contrariwise, this paper reports our findings on the positive impacts of using high-cardinality attributes on credit card fraud detection. Thus, we present a new algorithm for domain reduction that preserves the fraud-detection capabilities. Experiments applying a deep feedforward neural network on real datasets from a major Brazilian financial institution have shown that, when measured by the F-1 metric, the inclusion of such attributes does improve fraud-detection quality. As a main contribution, this proposed algorithm was able to reduce attribute cardinality, improving the training times of a model while preserving its predictive capabilities.

A Data-Driven Approach for Extracting Representative Information From Large Datasets With Mixed Attributes

The rapid growth of information technology and Internet applications has provided users with an explosion of information. Mobile e-commerce applications and web search engines are of great interest in extracting representative information from the original abundant information. However, the information extracted by several existing methods, such as top-k, are often quite similar, which is difficult to meet users’ demand for diversified information. In order to increase the diversity of representative information, this article proposes a data-driven approach to automatically identifying a subset of the original dataset that can cover more themes and content. The data-driven approach consists of two stages. First, a new unified similarity measure is proposed for handling dataset with categorical and numeric attributes. We inject external knowledge and attribute interactions into the similarity learning process to improve the accuracy of similarity estimation between data objects. Second, we develop an enhanced density peaks clustering algorithm based on shared nearest neighbors to automatically identify representative objects according to the previous estimated similarity. The enhanced density peaks algorithm takes the local structure in the entire data space into consideration, which makes the proposed approach relatively insensitive to variations in dataset’ density and dimensionality. Theoretical analysis demonstrates that the time complexity of the proposed approach can achieve the best $\bm {O}({\bm {N}\log \bm {N}})$ . Extensive comparison experiments were conducted on artificial and real-world datasets. The experimental results demonstrate the effectiveness and robustness of the proposed approach.

Categorical Data Clustering Using Harmony Search Algorithm for Healthcare Datasets

Healthcare analytics provide many benefits in healthcare dashboard systems. Healthcare datasets majorly contains categorical attributes. This paper proposed an optimized clustering for healthcare dataset named harmony search based categorical clustering (HSCC). The existing k-modes clustering algorithm is one of the well-known categorical data-clustering algorithm. Since the k-modes algorithm produces local optimal clusters. Generally, researchers use genetic algorithm (GA) based clustering algorithms to converge locally optimal solutions to global optimal solutions. GA has some deficiencies such as premature convergence with low speed. In this paper, harmony search (HS) optimization algorithm used to optimize clustering results. The result shows the proposed HSCC algorithm produced global optimized solution, unbiased and matured results. HSCC produces 98% accuracy for dental and 71% for lung cancer dataset. While GACC produces 95% and 65% accuracy for dental dataset and lung cancer dataset.

Sketch+ for Visual and Correlation-Based Exploratory Data Analysis: A Case Study with COVID-19 Databases

The amount of data daily generated by different sources grows exponentially and brings new challenges to the information technology experts. The recorded data usually include heterogeneous attribute types, such as the traditional date, numerical, textual, and categorical information, as well as complex ones, such as images, videos, and multidimensional data. Simply posing similarity queries over such records can underestimate the semantics and potential usefulness of particular attributes. In this context, the Exploratory Data Analysis (EDA) technology is well-suited to understand data and perform knowledge extraction and visualization of existing patterns. In this paper, we propose Sketch+ , a technique and a corresponding supporting tool to compare electronic health records (provided by hospitals) by similarity, supporting correlation-based exploratory analysis over attributes of different types and allowing data preprocessing tasks for visualization and knowledge extraction. Sketch+ computes partial and overall data correlation considering distance spaces induced by the attributes. It employs both ANOVA and association rules with lift correlations to study relationships between variables, allowing extensive data analysis. Among the tools provided, a pixel-oriented one drives the analysts to observe visual correlations among dates, categorical and numerical attributes. As a running case study, we employed three open databases of COVID-19 cases, showing that specialists can benefit from the inference modules of Sketch+ to analyze electronic records. The study highlights how Sketch+ can be employed to spot strong correlations among tuples and attributes, with statistically significant results. The exploratory analysis has been shown to be an essential complement for similarity search tasks, identifying and evaluating patterns from heterogeneous attributes.

Sarve: synthetic data and local differential privacy for private frequency estimation

The collection of user attributes by service providers is a double-edged sword. They are instrumental in driving statistical analysis to train more accurate predictive models like recommenders. The analysis of the collected user data includes frequency estimation for categorical attributes. Nonetheless, the users deserve privacy guarantees against inadvertent identity disclosures. Therefore algorithms called frequency oracles were developed to randomize or perturb user attributes and estimate the frequencies of their values. We propose Sarve, a frequency oracle that used Randomized Aggregatable Privacy-Preserving Ordinal Response (RAPPOR) and Hadamard Response (HR) for randomization in combination with fake data. The design of a service-oriented architecture must consider two types of complexities, namely computational and communication. The functions of such systems aim to minimize the two complexities and therefore, the choice of privacy-enhancing methods must be a calculated decision. The variant of RAPPOR we had used was realized through bloom filters. A bloom filter is a memory-efficient data structure that offers time complexity of O(1). On the other hand, HR has been proven to give the best communication costs of the order of log(b) for b-bits communication. Therefore, Sarve is a step towards frequency oracles that exhibit how privacy provisions of existing methods can be combined with those of fake data to achieve statistical results comparable to the original data. Sarve also implemented an adaptive solution enhanced from the work of Arcolezi et al. The use of RAPPOR was found to provide better privacy-utility tradeoffs for specific privacy budgets in both high and general privacy regimes.

Multigranulation Relative Entropy-Based Mixed Attribute Outlier Detection in Neighborhood Systems

Outlier detection is widely used in many fields, such as intrusion detection, credit card fraud detection, medical diagnosis, and so on. Existing outlier detection algorithms are mostly designed for dealing with numeric or categorical attributes. However, data usually exist in the form of mixed attributes in real-world applications. In this article, we propose a novel mixed attribute outlier detection method based on multigranulation relative entropy by employing the neighborhood rough set. First, the neighborhood system is constructed by optimizing the mixed distance metric and the radius of the statistical value. Second, the neighborhood entropy is introduced as an uncertainty measure of data. Furthermore, the three kinds of multigranulation relative entropy-based matrices are defined by three kinds of attribute sequences, and the multigranulation relative entropy-based outlier factor is integrated to indicate the outlier degree of every object. Based on the proposed outlier detection model, the corresponding algorithm is designed. Finally, the proposed algorithm is compared with other nine algorithms through experiments on public data. The experimental results show that the proposed technique is adaptive and effective.

Categorical Attribute traNsformation Environment (CANE): A python module for categorical to numeric data preprocessing

Categorical Attribute traNsformation Environment (CANE) is a simpler but powerful data categorical preprocessing Python package. The package is valuable since there is currently a large range of Machine Learning (ML) algorithms that can only be trained using numerical data (e.g., Deep Learning, Support Vector Machines) and several real-world ML applications are associated with categorical data attributes. Currently, CANE offers three categorical to numeric transformation methods, namely: Percentage Categorical Pruned (PCP), Inverse Document Frequency (IDF) and a simpler One-Hot-Encoding method. Additionally, the CANE module is well documented with several code examples that can help in its adoption by non expert users.

Building clustering for regional seismic response and damage analysis

This article presents a framework to cluster buildings into typologically similar groups and select indicator buildings for regional seismic response and damage analysis. The framework requires a robust database of buildings to provide high-level structural and site information of buildings. Here, a database of 234 reinforced concrete buildings with five or more above-ground stories in the central business district of Wellington, New Zealand, has been selected as the case study of this research. First, key structural and site parameters that contribute to the seismic demand, response, and damage of each building are extracted from the database. Extracted parameters comprise three numerical and five categorical attributes of each building, including the year of construction, height, period, lateral load resisting system, floor system, site subsoil class, importance level, and strong motion station. Next, two prominent unsupervised machine learning clustering approaches are utilized to cluster the mixed categorical and numerical building database: k-prototype on the mixed numerical and categorical database and k-means on principal components numerical subspace adopted from factor analysis of mixed data (FAMD). A novel autoencoder deep learning neural network is also designed and trained to convert the mixed data into a low-dimensional subspace called latent space and feed this into k-means for clustering. The proposed autoencoder method is demonstrated to be more effective at clustering buildings into useful typological clusters for seismic response and damage analysis based on multiple criteria from both data-science and engineering perspectives. The details of selected indicator buildings for each similar seismic vulnerability cluster are also represented.

A High Time-Efficient Missing Tag Detection Scheme for Integrated RFID Systems.

Missing tag incidents are common in RFID-enabled supply-chain and warehousing scenarios due to cargo theft and employee error operations, which may lead to serious economic losses or potential safety hazards. On the premise of ensuring the accuracy of missing tag detection, this paper aims to improve the time efficiency in an integrated RFID system. Unlike prior work focusing on detecting missing items from a large number of homogeneous tags that are monitored by a single reader, one integrated RFID system possesses multiple readers to communicate with the heterogeneous tags, which have different categorical attributes. In addition, the prior work required repeating the execution several times to capture the missing tags in assorted categories, which is of low time efficiency. Thus, a protocol called Multi-reader Missing Tag Detection (MMTD) is proposed to capture the missing tag quickly and reliably, which can detect missing tags from different categories in a parallel manner and is much more time-efficient than previous work. MMTD has two major advantages compared to prior work: (i) It leverages the knowledge of the spatial distribution of tags to divide up a difficult detection task into several lightweight tasks, which are shared by multiple readers. (ii) It personalizes the time frame of the reader based on the tag population to optimize the utilization of the communication channel. The final simulation results reveal that MMTD is the best in time-efficiency among the comparison protocols, and MMTD outperforms the other missing tag detection protocols by at least in the Integrated RFID scenarios.

A novel method for assessing and measuring homophily in networks through second-order statistics

We present a new method for assessing and measuring homophily in networks whose nodes have categorical attributes, namely when the nodes of networks come partitioned into classes (colors). We probe this method in two different classes of networks: (i) protein–protein interaction (PPI) networks, where nodes correspond to proteins, partitioned according to their functional role, and edges represent functional interactions between proteins (ii) Pokec on-line social network, where nodes correspond to users, partitioned according to their age, and edges respresent friendship between users.Similarly to other classical and well consolidated approaches, our method compares the relative edge density of the subgraphs induced by each class with the corresponding expected relative edge density under a null model. The novelty of our approach consists in prescribing an endogenous null model, namely, the sample space of the null model is built on the input network itself. This allows us to give exact explicit expression for the {mathbf {z}}-score of the relative edge density of each class as well as other related statistics. The {mathbf {z}}-scores directly quantify the statistical significance of the observed homophily via Čebyšëv inequality. The expression of each {mathbf {z}}-score is entered by the network structure through basic combinatorial invariant such as the number of subgraphs with two spanning edges. Each {mathbf {z}}-score is computed in O(n+m) time for a network with n nodes and m edges. This leads to an overall efficient computational method for assesing homophily. We complement the analysis of homophily/heterophily by considering {mathbf {z}}-scores of the number of isolated nodes in the subgraphs induced by each class, that are computed in O(nm) time. Theoretical results are then exploited to show that, as expected, both the analyzed network classes are significantly homophilic with respect to the considered node properties.

DP-k-modes: A self-tuning k-modes clustering algorithm

• Self-tuning cutoff distance is proposed to extend DPC. • Optimal initial seeds and number of clusters determined simultaneously. • New dissimilarity measure is proposed calculating dissimilarities between objects. • Self-tuning k-modes clustering algorithm , referred to as DP-k-modes, is proposed. • DP-k-modes is superior to the compared ones and is significant different to them. The k -modes clustering algorithm was proposed by Huang for handling datasets with categorical attributes, however, the dissimilarity measure used limits its applicability. Ng et al. improved on Huang’s k -modes algorithm by proposing a new dissimilarity measure between objects. Moreover, both k -modes algorithms require the initial seeds to be randomly chosen and the number of clusters be specified manually. To overcome the limitations of Huang’s and Ng’s k -modes clustering algorithms, we first extend the clustering algorithm published in Science in 2014 (“clustering by fast search and find of density peaks”). The optimal initial seeds and the number of clusters of a dataset are determined simultaneously by taking the standard deviation as the self-tuning cutoff distance and the simple match dissimilarity as the distance measurement in the definition of the density of a point. A new dissimilarity measure is proposed to calculate the dissimilarities between objects to improve on that of Ng’s k -modes algorithm. The performance of our resulting self-tuning k -modes clustering algorithm was tested on nine datasets (three being relatively large) from the UCI (University of California in Irvine) machine learning repository. The clustering results were compared to those produced by Huang’s and Ng’s algorithms. Statistical tests of three k -modes algorithms were undertaken to determine whether or not there is significant difference between our self-tuning k -modes algorithm and Huang’s and Ng’s k -modes algorithms. All these experimental results demonstrate that our proposed k -modes clustering algorithm is superior to Hang’s and Ng’s k -modes algorithms in terms of clustering accuracy ( ACC ) and the well-known Adjusted Rand Index ( ARI ) metric. Our self-tuning k -modes algorithm is significantly different from both Huang’s and Ng’s k -modes algorithms, and there is no statistically significant difference between Ng’s and Huang’s k -modes algorithms.

Efficient analysis of COVID-19 clinical data using machine learning models.

Because of the rapid spread of COVID-19 to almost every part of the globe, huge volumes of data and case studies have been made available, providing researchers with a unique opportunity to find trends and make discoveries like never before by leveraging such big data. This data is of many different varieties and can be of different levels of veracity, e.g., precise, imprecise, uncertain, and missing, making it challenging to extract meaningful information from such data. Yet, efficient analyses of this continuously growing and evolving COVID-19 data is crucial to inform — often in real-time — the relevant measures needed for controlling, mitigating, and ultimately avoiding viral spread. Applying machine learning-based algorithms to this big data is a natural approach to take to this aim since they can quickly scale to such data and extract the relevant information in the presence of variety and different levels of veracity. This is important for COVID-19 and potential future pandemics in general. In this paper, we design a straightforward encoding of clinical data (on categorical attributes) into a fixed-length feature vector representation and then propose a model that first performs efficient feature selection from such representation. We apply this approach to two clinical datasets of the COVID-19 patients and then apply different machine learning algorithms downstream for classification purposes. We show that with the efficient feature selection algorithm, we can achieve a prediction accuracy of more than 90% in most cases. We also computed the importance of different attributes in the dataset using information gain. This can help the policymakers focus on only certain attributes to study this disease rather than focusing on multiple random factors that may not be very informative to patient outcomes.Graphical abstract

Close relationship: a theoretical survey of research and conceptualisation of the model

The article presents a conceptual model of close relationships. Close relationships are a specific and multicomponent phenomenon in the living space of modernity. On the basis of the analysis of sources and rethinking of the data obtained earlier, close relationships are considered as a type of interpersonal relations. It is a meaningful, selective relationship of people aimed at satisfying their need for love and belonging, based on affiliative feelings and attachment. Closeness in relationships is defined as a structural property of the dyad, including the strength, frequency, psychological distance, the variety of interrelationships that exist between people. It is noted that close relationships are set by social roles. Reciprocal roles, for example, parent and child, husband and wife set the initial belonging of these relationships to the category of close, but do not guarantee the presence in them of intimacy as a qualitative characteristic. The invariant (partners' attachment to each other, emotional experiences, psychological distance; value-semantic unity; involvement) categorical attributes of close relationships were identified. The variation signs characterising their main types (romantic, marital, friendship, love, kinship) are described. It is noted that the dynamics conditioned by the totality of factors determines the variety of close relationships – dysfunctional and functional. We understood the limitations and prospects for further developments in this area.

How big will the next eruption be?

Anticipating the size of the next volcanic eruption in long-term forecasts is a major problem in both basic and applied volcanology. In this study, we investigate the extent to which eruption size is predictable based on historical and other attribute data. Data from the Smithsonian Global Volcanism Program (GVP) Catalog is used to determine the predictability of volcanic eruption size as quantified through the reported VEI (Volcano Explosivity Index). The numerical and categorical attributes from the global volcanic catalog were classified with trained random forest and simple prediction models to make a forecast of VEI that can be tested against the most recent eruption of each volcano. We compare these results to two different baseline predictability levels by: (a) selecting randomly from the global distribution of VEIs for the most recent eruptions to calculate a cohort baseline and (b) selecting the most frequent VEI for a given population to calculate a zero-rule baseline. We found that: (1) nearly any method that incorporates prior information on a specific volcano improves the prediction accuracy of the succeeding eruption VEI by at least 10 percentage points relative to the cohort baseline case, (2) incorporating attributes beyond previous VEIs can provide better accuracy and achieve up to 30 percentage point accuracy gains, (3) total accuracy of the VEI forecasting by these methods can be up to nearly 80% and (4) the zero-rule is an effective prediction method that is modestly outperformed (~ 5 percentage point gain) by random forest methods with multiple attributes on most datasets. We find no notable preference in accuracy based on volcano type. The results quantify the importance of volcano-specific information in long-term forecasting and may help practitioners assess their expected performance when anticipating future eruption size.

Machine learning models to predict neuropsychiatric disorders in various brain tumors

Objective Neuropsychiatric disorders in brain tumor patients are commonly observed. It is difficult to anticipate these disorders in different types of brain tumors. The goal of the study was to see how well machine learning (ML)-based decision algorithms might predict neuropsychiatric problems in different types of brain tumors. Methods 145 histopathologically-confirmed primary brain tumors of both gender aged 25–65 years of age, were included for neuropsychiatric assessments. The datasets of brain tumor patients were employed for building the models. Four different decision ML classification trees/models (J48, Random Forest, Random Tree & Hoeffding Tree) with supervised learning were trained, tested, and validated on class labeled data of brain tumor patients. The models were compared in order to determine the best accurate classifier in predicting neuropsychiatric problems in various brain tumors. Following categorical attributes as independent variables (predictors) were included from the data of brain tumor patients: age, gender, depression, dementia, and brain tumor types. With the machine learning decision tree/model techniques, a multi-target classification was performed with classes of neuropsychiatric diseases that were predicted from the selected attributes. Results 86 percent of patients were depressed, and 55 percent were suffering from dementia. Anger was the most often reported neuropsychiatric condition in brain tumor patients (92.41%), followed by sleep disorders (83%), apathy (80%), and mood swings (76.55%). When compared to other tumor types, glioblastoma patients had a higher rate of depression (20%) and dementia (20.25%). The developed models Random Forest and Random Tree were found successful with an accuracy of up to 94% (10-folds) for the prediction of neuropsychiatric disorders in brain tumor patients. The multiclass target (neuropsychiatric ailments) accuracies were having good measures of precision (0.9–1.0), recall (0.9–1.0), F-measure (0.9–1.0), and ROC area (0.9–1.0) in decision models. Conclusion Random Forest Trees can be used to accurately predict neuropsychiatric illnesses. Based on the model output, the ML-decision trees will aid the physician in pre-diagnosing the mental issue and deciding on the best therapeutic approach to avoid subsequent neuropsychiatric issues in brain tumor patients.

Evolutionary tree-based quasi identifier and federated gradient privacy preservations over big healthcare data

<span>Big data has remodeled the way organizations supervise, examine and leverage data in any industry. To safeguard sensitive data from public contraventions, several countries investigated this issue and carried out privacy protection mechanism. With the aid of quasi-identifiers privacy is not said to be preserved to a greater extent. This paper proposes a method called evolutionary tree-based quasi-identifier and federated gradient (ETQI-FD) for privacy preservations over big healthcare data. The first step involved in the ETQI-FD is learning quasi-identifiers. Learning quasi-identifiers by employing information loss function separately for categorical and numerical attributes accomplishes both the largest dissimilarities and partition without a comprehensive exploration between tuples of features or attributes. Next with the learnt quasi-identifiers, privacy preservation of data item is made by applying federated gradient arbitrary privacy preservation learning model. This model attains optimal balance between privacy and accuracy. In the federated gradient privacy preservation learning model, we evaluate the determinant of each attribute to the outputs. Then injecting Adaptive Lorentz noise to data attributes our ETQI-FD significantly minimizes the influence of noise on the final results and therefore contributing to privacy and accuracy. An experimental evaluation of ETQI-FD method achieves better accuracy and privacy than the existing methods.</span>

Pengelompokan wilayah menurut potensi ekonomi menggunakan modifikasi algoritme fuzzy k-prototypes untuk penentuan target pembangunan desa

The clustering algorithm can group regions based on economic potential with mixed attributes data, consisting of numeric and categorical data. This study aims to group villages according to their economic potential in determining village development targets in Demak Regency using the fuzzy k-prototypes algorithm and modified Eskin distance to measure the distance of categorical attributes. The data used are PODES2018 data and the 2019 Wilkerstat Mapping. Village clustering produces three village clusters according to their economic potential, namely low, medium, and high economic clusters. Clusters of high economic potential are located on the main transportation routes of Semarang–Kudus and Semarang–Grobogan. However, villages on the main transportation route are still included in the low economic cluster. Considering the status of the urban/rural village classification, most of these villages are included in the urban village category. The results of this clustering can be used to determine village development targets in increasing the Village Developing Index in Demak Regency.

Application of C4.5 Algorithm to Prediction Sales at PT. Sumber Sayur Segar

Fresh vegetables, fruits and fresh meat are one of the basic needs for human life. The need for fresh vegetables, fruits and meat is one of the most important factors for buyers before making a purchase transaction. Likewise with the needs of fresh vegetables, fruit and meat needed by restaurants, cafes, hospitals, hotels and so on. With the increasing number of requests from customers for the needs of fresh vegetables, fruit and meat, companies engaged in the supply and sale of these necessities need to record sales transactions so that there are no stock vacancies and excess stock of goods. Therefore, companies must be more careful in providing fresh vegetables, fruits and meat which are in great demand, so it needs a data processing in the form of data mining using the C4.5 algorithm. In this study, the predicted sales transactions are the last three months of January, February and March 2021. Then for the sales prediction criteria used are in the form of price, type of goods, type of unit and month of sale so that from these criteria can be obtained sales transactions that are selling or not selling. Data mining is a process of mining important information from a very large data. While the C4.5 algorithm is a data classification that has numeric and categorical attributes, where the results of the classification process in the form of rules can be used to predict the value of discrete type attributes from new records. The system was built using the PHP programming language and MySQL as the database. This study obtained predictive results which were implemented in the form of a decision tree, namely the category of types of vegetables belonging to the best-selling sales transactions.

Evaluating Data‐type Heterogeneity in Interactive Visual Analyses with Parallel Axes

AbstractThe application of parallel axes for the interactive visual analysis of multidimensional data is a widely used concept. While multidimensional data sets are commonly heterogeneous in nature, i.e. data items contain both numerical and categorical (including ordinal) attribute values, the use of parallel axes often assumes either numerical or categorical attributes. While Parallel Coordinates and their large variety of extensions focus on numerical data, Parallel Sets and related methods focus on categorical attributes. While both concepts allow for displaying heterogeneous data, no clear strategies have been defined for representing categories in Parallel Coordinates or discretization of continuous ranges in Parallel Sets. In practice, type conversion as a pre‐processing step can be used as well as coordinated views of numerical and categorical data visualizations. We evaluate traditional and state‐of‐the‐art approaches with respect to the interplay of categorical and numerical dimensions for querying probability‐based events. We also compare against a heterogeneous Parallel Coordinates/Parallel Set approach with a novel interface between categorical and numerical axes . We show that approaches for mapping categorical data to numerical axis representations can lead to lower accuracy in answering probability‐based questions and higher response times than hybrid approaches in multiple‐event scenarios.