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Ensemble Learning to Improve Machine Learning Results

#artificialintelligence

Ensemble methods are meta-algorithms that combine several machine learning techniques into one predictive model in order to decrease variance (bagging), bias (boosting), or improve predictions (stacking). Ensemble learning helps improve machine learning results by combining several models. This approach allows the production of better predictive performance compared to a single model. That is why ensemble methods placed first in many prestigious machine learning competitions, such as the Netflix Competition, KDD 2009, and Kaggle. The Statsbot team wanted to give you the advantage of this approach and asked a data scientist, Vadim Smolyakov, to dive into three basic ensemble learning techniques.


Ensemble Learning to Improve Machine Learning Results

#artificialintelligence

Ensemble methods are meta-algorithms that combine several machine learning techniques into one predictive model in order to decrease variance (bagging), bias (boosting), or improve predictions (stacking). Most ensemble methods use a single base learning algorithm to produce homogeneous base learners, i.e. learners of the same type, leading to homogeneous ensembles. There are also some methods that use heterogeneous learners, i.e. learners of different types, leading to heterogeneous ensembles. In order for ensemble methods to be more accurate than any of its individual members, the base learners have to be as accurate as possible and as diverse as possible. Bagging stands for bootstrap aggregation.


A Comprehensive Guide to Ensemble Learning - What Exactly Do You Need to Know - neptune.ai

#artificialintelligence

Ensemble learning techniques have been proven to yield better performance on machine learning problems. We can use these techniques for regression as well as classification problems. The final prediction from these ensembling techniques is obtained by combining results from several base models. Averaging, voting and stacking are some of the ways the results are combined to obtain a final prediction. In this article, we will explore how ensemble learning can be used to come up with optimal machine learning models. Ensemble learning is a combination of several machine learning models in one problem.


Ensembles in Machine Learning

#artificialintelligence

Ensemble methods are well established as an algorithmic cornerstone in machine learning (ML). Just as in real life, in ML a committee of experts will often perform better than an individual provided appropriate care is taken in constituting the committee. Since the earliest days of ML research, a variety of ensemble strategies have been developed with random forests and gradient boosting emerging as leading-edge methods in classification today. It has been recognised since the early days of ML research that ensembles of classifiers can be more accurate than individual models. In ML, ensembles are effectively committees that aggregate the predictions of individual classifiers. They are effective for very much the same reasons a committee of experts works in human decision making, they can bring different expertise to bear and the averaging effect can reduce errors. This article presents a tutorial on the main ensemble methods in use in ML with links to Python notebooks and datasets illustrating these methods in action. The objective is to help practitioners get started with ML ensembles and to provide an insight into when and why ensembles are effective. There have been a lot of developments since then and the ensemble idea is still to the forefront in ML applications. For example, random forests [2] and gradient boosting [7] would be considered among the most powerful methods available to ML practitioners today. The generic ensemble idea is presented in Figure 1. All ensembles are made up of a collection of base classifiers, also known as members or estimators.


A meta-algorithm for classification using random recursive tree ensembles: A high energy physics application

arXiv.org Machine Learning

The aim of this work is to propose a meta-algorithm for automatic classification in the presence of discrete binary classes. Classifier learning in the presence of overlapping class distributions is a challenging problem in machine learning. Overlapping classes are described by the presence of ambiguous areas in the feature space with a high density of points belonging to both classes. This often occurs in real-world datasets, one such example is numeric data denoting properties of particle decays derived from high-energy accelerators like the Large Hadron Collider (LHC). A significant body of research targeting the class overlap problem use ensemble classifiers to boost the performance of algorithms by using them iteratively in multiple stages or using multiple copies of the same model on different subsets of the input training data. The former is called boosting and the latter is called bagging. The algorithm proposed in this thesis targets a challenging classification problem in high energy physics - that of improving the statistical significance of the Higgs discovery. The underlying dataset used to train the algorithm is experimental data built from the official ATLAS full-detector simulation with Higgs events (signal) mixed with different background events (background) that closely mimic the statistical properties of the signal generating class overlap. The algorithm proposed is a variant of the classical boosted decision tree which is known to be one of the most successful analysis techniques in experimental physics. The algorithm utilizes a unified framework that combines two meta-learning techniques - bagging and boosting. The results show that this combination only works in the presence of a randomization trick in the base learners.