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Ensemble Learning
In statistics and machine learning, ensemble methods use multiple learning algorithms to obtain better predictive performance than could be obtained from any of the constituent learning algorithms alone. Unlike a statistical ensemble in statistical mechanics, which is usually infinite, a machine learning ensemble consists of only a concrete finite set of alternative models, but typically allows for much more flexible structure to exist among those alternatives. Overview Supervised learning algorithms search through a hypothesis space to find a suitable hypothesis that will make good predictions with a particular problem. Even if this space contains hypotheses that are very well-suited for a particular problem, it may be very difficult to find a good one. Ensembles combine multiple hypotheses to form one which should be theoretically better. ''Ensemble learning'' trains two or more machine learning algorithms on a specific classification or regression task. The algorithms wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Statistics
Statistics (from German language, German: ', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statistical model to be studied. Populations can be diverse groups of people or objects such as "all people living in a country" or "every atom composing a crystal". Statistics deals with every aspect of data, including the planning of data collection in terms of the design of statistical survey, surveys and experimental design, experiments. When census data (comprising every member of the target population) cannot be collected, statisticians collect data by developing specific experiment designs and survey sample (statistics), samples. Representative sampling assures that inferences and conclusions can reasonably extend from the sample ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Consensus Clustering
Consensus clustering is a method of aggregating (potentially conflicting) results from multiple clustering algorithms. Also called cluster ensembles or aggregation of clustering (or partitions), it refers to the situation in which a number of different (input) clusterings have been obtained for a particular dataset and it is desired to find a single (consensus) clustering which is a better fit in some sense than the existing clusterings. Consensus clustering is thus the problem of reconciling clustering information about the same data set coming from different sources or from different runs of the same algorithm. When cast as an optimization problem, consensus clustering is known as median partition, and has been shown to be NP-complete, even when the number of input clusterings is three. Consensus clustering for unsupervised learning is analogous to ensemble learning in supervised learning. Issues with existing clustering techniques * Current clustering techniques do not address a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Akaike Information Criterion
The Akaike information criterion (AIC) is an estimator of prediction error and thereby relative quality of statistical models for a given set of data. Given a collection of models for the data, AIC estimates the quality of each model, relative to each of the other models. Thus, AIC provides a means for model selection. AIC is founded on information theory. When a statistical model is used to represent the process that generated the data, the representation will almost never be exact; so some information will be lost by using the model to represent the process. AIC estimates the relative amount of information lost by a given model: the less information a model loses, the higher the quality of that model. In estimating the amount of information lost by a model, AIC deals with the trade-off between the goodness of fit of the model and the simplicity of the model. In other words, AIC deals with both the risk of overfitting and the risk of underfitting. The Akaike information crite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bayesian Information Criterion
In statistics, the Bayesian information criterion (BIC) or Schwarz information criterion (also SIC, SBC, SBIC) is a criterion for model selection among a finite set of models; models with lower BIC are generally preferred. It is based, in part, on the likelihood function and it is closely related to the Akaike information criterion (AIC). When fitting models, it is possible to increase the maximum likelihood by adding parameters, but doing so may result in overfitting. Both BIC and AIC attempt to resolve this problem by introducing a penalty term for the number of parameters in the model; the penalty term is larger in BIC than in AIC for sample sizes greater than 7. The BIC was developed by Gideon E. Schwarz and published in a 1978 paper, as a large-sample approximation to the Bayes factor. Definition The BIC is formally defined as : \mathrm = k\ln(n) - 2\ln(\widehat L). \ where *\hat L = the maximized value of the likelihood function of the model M, i.e. \hat L=p(x\mid\wid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Stepwise Regression
In statistics, stepwise regression is a method of fitting regression models in which the choice of predictive variables is carried out by an automatic procedure. In each step, a variable is considered for addition to or subtraction from the set of explanatory variables based on some prespecified criterion. Usually, this takes the form of a forward, backward, or combined sequence of ''F''-tests or ''t''-tests. The frequent practice of fitting the final selected model followed by reporting estimates and confidence intervals without adjusting them to take the model building process into account has led to calls to stop using stepwise model building altogetherFlom, P. L. and Cassell, D. L. (2007) "Stopping stepwise: Why stepwise and similar selection methods are bad, and what you should use," NESUG 2007. or to at least make sure model uncertainty is correctly reflected by using prespecified, automatic criteria together with more complex standard error estimates that remain unbiased. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Adaboost
AdaBoost (short for Adaptive Boosting) is a statistical classification meta-algorithm formulated by Yoav Freund and Robert Schapire in 1995, who won the 2003 Gödel Prize for their work. It can be used in conjunction with many types of learning algorithm to improve performance. The output of multiple ''weak learners'' is combined into a weighted sum that represents the final output of the boosted classifier. Usually, AdaBoost is presented for binary classification, although it can be generalized to multiple classes or bounded intervals of real values. AdaBoost is adaptive in the sense that subsequent weak learners (models) are adjusted in favor of instances misclassified by previous models. In some problems, it can be less susceptible to overfitting than other learning algorithms. The individual learners can be weak, but as long as the performance of each one is slightly better than random guessing, the final model can be proven to converge to a strong learner. Although AdaBo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ensemble Aggregation
Ensemble may refer to: Art * Architectural ensemble * ''Ensemble'' (Kendji Girac album), 2015 * ''Ensemble'' (Ensemble album), 2006 * Ensemble (band), a project of Olivier Alary * Ensemble cast (drama, comedy) * Ensemble (musical theatre), also known as the chorus * ''Ensemble'' (Stockhausen), 1967 group-composition project by Karlheinz Stockhausen * Musical ensemble Mathematics and science * Distribution ensemble or probability ensemble (cryptography) * Ensemble Kalman filter * Ensemble learning (statistics and machine learning) * Ensembl genome database project * Neural ensemble, a population of nervous system cells (or cultured neurons) involved in a particular neural computation * Statistical ensemble (mathematical physics) ** Climate ensemble ** Ensemble average (statistical mechanics) ** Ensemble averaging (machine learning) ** Ensemble (fluid mechanics) ** Ensemble forecasting (meteorology) ** Quantum statistical mechanics, the study of statistical ensembles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Random Forest
Random forests or random decision forests is an ensemble learning method for statistical classification, classification, regression analysis, regression and other tasks that works by creating a multitude of decision tree learning, decision trees during training. For classification tasks, the output of the random forest is the class selected by most trees. For regression tasks, the output is the average of the predictions of the trees. Random forests correct for decision trees' habit of overfitting to their Test set, training set. The first algorithm for random decision forests was created in 1995 by Tin Kam Ho using the random subspace method, which, in Ho's formulation, is a way to implement the "stochastic discrimination" approach to classification proposed by Eugene Kleinberg. An extension of the algorithm was developed by Leo Breiman and Adele Cutler, who registered "Random Forests" as a trademark in 2006 (, owned by Minitab, Minitab, Inc.). The extension combines Breiman's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bootstrap Set Generation
Bootstrapping is a self-starting process that is supposed to proceed without external input. Bootstrapping, bootstrap, or bootstraps may also refer to: * Bootstrap (front-end framework), a free collection of tools for creating websites and web applications * Bootstrap curriculum, a curriculum which uses computer programming to teach algebra to students age 12–16 * Bootstrap funding in entrepreneurship and startups * Bootstrap model, a class of theories in quantum physics * Conformal bootstrap, a mathematical method to constrain and solve models in particle physics * Bootstrapping (compilers), the process of writing a compiler in the programming language it is intended to compile * Bootstrapping (electronics), a type of circuit that employs positive feedback * Bootstrapping (finance), a method for constructing a yield curve from the prices of coupon-bearing products * Bootstrapping (law), a former rule of evidence in U.S. federal conspiracy trials * Bootstrapping (linguistics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Bayes' Theorem
Bayes' theorem (alternatively Bayes' law or Bayes' rule, after Thomas Bayes) gives a mathematical rule for inverting Conditional probability, conditional probabilities, allowing one to find the probability of a cause given its effect. For example, if the risk of developing health problems is known to increase with age, Bayes' theorem allows the risk to someone of a known age to be assessed more accurately by conditioning it relative to their age, rather than assuming that the person is typical of the population as a whole. Based on Bayes' law, both the prevalence of a disease in a given population and the error rate of an infectious disease test must be taken into account to evaluate the meaning of a positive test result and avoid the ''base-rate fallacy''. One of Bayes' theorem's many applications is Bayesian inference, an approach to statistical inference, where it is used to invert the probability of Realization (probability), observations given a model configuration (i.e., th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Naive Bayes Classifier
In statistics, naive (sometimes simple or idiot's) Bayes classifiers are a family of " probabilistic classifiers" which assumes that the features are conditionally independent, given the target class. In other words, a naive Bayes model assumes the information about the class provided by each variable is unrelated to the information from the others, with no information shared between the predictors. The highly unrealistic nature of this assumption, called the naive independence assumption, is what gives the classifier its name. These classifiers are some of the simplest Bayesian network models. Naive Bayes classifiers generally perform worse than more advanced models like logistic regressions, especially at quantifying uncertainty (with naive Bayes models often producing wildly overconfident probabilities). However, they are highly scalable, requiring only one parameter for each feature or predictor in a learning problem. Maximum-likelihood training can be done by evaluating a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Tom M
Tom or TOM may refer to: * Tom (given name), including a list of people and fictional characters with the name. Arts and entertainment Film and television * ''Tom'' (1973 film), or ''The Bad Bunch'', a blaxploitation film * ''Tom'' (2002 film), a documentary film * ''Tom'' (American TV series), 1994 * ''Tom'' (Spanish TV series), 2003 Music * ''Tom'', a 1970 album by Tom Jones * Tom drum, a musical drum with no snares * Tom (Ethiopian instrument), a plucked lamellophone thumb piano * Tune-o-matic, a guitar bridge design Places * Tom, Oklahoma, US * Tom (Amur Oblast), a river in Russia * Tom (river), in Russia, a right tributary of the Ob Science and technology * A male cat * A male wild turkey * Tom (pattern matching language), a programming language * TOM (psychedelic), a hallucinogen * Text Object Model, a Microsoft Windows programming interface * Theory of mind (ToM), in psychology * Translocase of the outer membrane, a complex of proteins Transportation * ''To ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |