An approach for improved students’ performance prediction using homogeneous and heterogeneous ensemble methods

Web-based learning technologies of educational institutions store a massive amount of interaction data which can be helpful to predict students’ performance through the aid of machine learning algorithms. With this, various researchers focused on studying ensemble learning methods as it is known to improve the predictive accuracy of traditional classification algorithms. This study proposed an approach for enhancing the performance prediction of different single classification algorithms by using them as base classifiers of homogeneous ensembles (bagging and boosting) and heterogeneous ensembles (voting and stacking). The model utilized various single classifiers such as multilayer perceptron or neural networks (NN), random forest (RF), naïve Bayes (NB), J48, JRip, OneR, logistic regression (LR), k-nearest neighbor (KNN), and support vector machine (SVM) to determine the base classifiers of the ensembles. In addition, the study made use of the University of California Irvine (UCI) open-access student dataset to predict students’ performance. The comparative analysis of the model’s accuracy showed that the best-performing single classifier’s accuracy increased further from 93.10% to 93.68% when used as a base classifier of a voting ensemble method. Moreover, results in this study showed that voting heterogeneous ensemble performed slightly better than bagging and boosting homogeneous ensemble methods

An approach for improved students’ performance prediction using homogeneous and heterogeneous ensemble methods

Web-based learning technologies of educational institutions store a massive amount of interaction data which can be helpful to predict students’ performance through the aid of machine learning algorithms. With this, various researchers focused on studying ensemble learning methods as it is known to improve the predictive accuracy of traditional classification algorithms. This study proposed an approach for enhancing the performance prediction of different single classification algorithms by using them as base classifiers of homogeneous ensembles (bagging and boosting) and heterogeneous ensembles (voting and stacking). The model utilized various single classifiers such as multilayer perceptron or neural networks (NN), random forest (RF), naïve Bayes (NB), J48, JRip, OneR, logistic regression (LR), k-nearest neighbor (KNN), and support vector machine (SVM) to determine the base classifiers of the ensembles. In addition, the study made use of the University of California Irvine (UCI) open-access student dataset to predict students’ performance. The comparative analysis of the model’s accuracy showed that the best-performing single classifier’s accuracy increased further from 93.10% to 93.68% when used as a base classifier of a voting ensemble method. Moreover, results in this study showed that voting heterogeneous ensemble performed slightly better than bagging and boosting homogeneous ensemble methods

Ensemble learning in the presence of noise

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Escuela Politécnica Superior, Departamento de Ingenieria Informática. Fecha de lectura: 14-02-2019La disponibilidad de grandes cantidades de datos provenientes de diversas fuentes ampl a enormemente las posibilidades para una explotaci on inteligente de la informaci on. No obstante, la extracci on de conocimiento a partir de datos en bruto es una tarea compleja que requiere el desarrollo de m etodos de aprendizaje e cientes y robustos. Una de las principales di cultades en el aprendizaje autom atico es la presencia de ruido en los datos. En esta tesis, abordamos el problema del aprendizaje autom atico en presencia de ruido. Para este prop osito, nos centraremos en el uso de conjuntos de clasi cadores. Nuestro objetivo es crear colecciones de aprendices base cuyos resultados, al ser combinados, mejoren no solo la precisi on sino tambi en la robustez de las predicciones. Una primera contribuci on de esta tesis es aprovechar el ratio de submuestreo para construir conjuntos de clasi cadores basados en bootstrap (como bagging o random forests) precisos y robustos. La idea de utilizar el submuestreo como mecanismo de regularizaci on tambi en se explota para la detecci on de ejemplos ruidosos. En concreto, los ejemplos que est an mal clasi cados por una fracci on de los miembros del conjunto se marcan como ruido. El valor optimo de este umbral se determina mediante validaci on cruzada. Las instancias ruidosas se eliminan ( ltrado) o se corrigen sus etiquetas de su clase (limpieza). Finalmente, se construye un conjunto de clasi cadores utilizando los datos de entrenamiento limpios ( ltrados o limpiados). Otra contribuci on de esta tesis es vote-boosting, un m etodo de conjuntos secuencial especialmente dise~nado para ser robusto al ruido en las etiquetas de clase. Vote-boosting reduce la excesiva sensibilidad a este tipo de ruido de los algoritmos basados en boosting, como adaboost. En general, los algoritmos basados en booting modi can la distribuci on de pesos en los datos de entrenamiento progresivamente para enfatizar instancias mal clasi cadas. Este enfoque codicioso puede terminar dando un peso excesivamente alto a instancias cuya etiqueta de clase sea incorrecta. Por el contrario, en vote-boosting, el enfasis se basa en el nivel de incertidumbre (acuerdo o desacuerdo) de la predicci on del conjunto, independientemente de la etiqueta de clase. Al igual que en boosting, voteboosting se puede analizar como una optimizaci on de descenso por gradiente en espacio funcional. Uno de los problemas abiertos en el aprendizaje de conjuntos es c omo construir combinaciones de clasi cadores fuertes. La principal di cultad es lograr diversidad entre los clasi cadores base sin un deterioro signi cativo de su rendimiento y sin aumentar en exceso el coste computacional. En esta tesis, proponemos construir conjuntos de SVM con la ayuda de mecanismos de aleatorizaci on y optimizaci on. Gracias a esta combinaci on de estrategias complementarias, es posible crear conjuntos de SVM que son mucho m as r apidos de entrenar y son potencialmente m as precisos que un SVM individual optimizado. Por ultimo, hemos desarrollado un procedimiento para construir conjuntos heterog eneos que interpolan sus decisiones a partir de conjuntos homog eneos compuestos por diferentes tipos de clasi cadores. La composici on optima del conjunto se determina mediante validaci on cruzada. v

Open-source neural architecture search with ensemble and pre-trained networks

The training and optimization of neural networks, using pre-trained, super learner and ensemble approaches is explored. Neural networks, and in particular Convolutional Neural Networks (CNNs), are often optimized using default parameters. Neural Architecture Search (NAS) enables multiple architectures to be evaluated prior to selection of the optimal architecture. Our contribution is to develop, and make available to the community, a system that integrates open source tools for the neural architecture search (OpenNAS) of image classification models. OpenNAS takes any dataset of grayscale, or RGB images, and generates the optimal CNN architecture. Particle Swarm Optimization (PSO), Ant Colony Optimization (ACO) and pre-trained models serve as base learners for ensembles. Meta learner algorithms are subsequently applied to these base learners and the ensemble performance on image classification problems is evaluated. Our results show that a stacked generalization ensemble of heterogeneous models is the most effective approach to image classification within OpenNAS