Boosting is a process of finding & combining weakly predictive models into a strongly predictive model.

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Boosting Explained

I'm a newbie trying to learn Boosting. The examples I found online are quite confusing. Is there a simple tutorial somewhere that explains ...
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GradientBoostClassifier(sklearn) takes very long time to train

I'm using dataset with 61879 datapoints and 102 features. On this dataset Randomforest(sklearn) takes less than 90s to train for 100 estimators while GradientBoostClassifier(sklearn) is taking forever ...
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20 views

Skewed Classification Problem

So I've read around and seen this is a problem. I have a classification problem and 12 variables ... I'm working on getting more, but even if l get the number to 20-30 I feel like the problem will ...
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36 views

Meaning of `max_depth` in GradientBoostingClassifier in scikit-learn

when I use the GradientBoostingClassifier from scikit-learn, I find that there is a parameter max_depth to set, which controls the maximum depth of the regression ...
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20 views

How to choose a regression tree (base learner) at each iteration of Gradient Tree Boosting?

I'm trying to understand Gradient Tree Boosting, by following Prof. Friedman's original paper: Greedy Function Approximation: A Gradient Boosting Machine. Basically, at each iteration, a regression ...
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25 views

Why does the equation $ -\sum^{n}_{t=1} \tilde{W}(t)_{m-1} y_{t}h(x; \theta_{m}) = 2 \epsilon_m -1$ hold in boosting?

I was trying to understand the boosting algorithm as described by the MIT graduate class lectures notes on ocw. On page 2 they give the outline of boosting as follows: The step that is not clear ...
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67 views

Boosted trees and Variable Interactions

How can one see in a Boosted trees classification model, which variables interact with each other and how much? I would like to make use o this in R gbm package if possible
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28 views

Value of the loss function and Classification Errors in gbm package (R)

I have a simple problem of classification (0s and 1s) using adaboost loss function. When I check the components of a boosted model using the gbm package I see: ...
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26 views

why boosting method is sensitive to outliers

I found many articles showing that boosting methods are sensitive to outliers, but no article explains why. In my experience, I feel outliers data is bad for any machine learning algorithms, but why ...
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25 views

Alternative to AIC for feature selection in classification

I want to know what are the most common methods for feature selection in classification problems (binary and mutli-class). I see in Chapter 6 of Zumel and Mount that they use AIC before they train ...
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38 views

what is the difference between bagging and boosting in random forest?

I understand what is bagging and how it is applied to random forest. But how is bagging different from boosting. If boosting is different from bagging, how can boosting be applied to random forest?
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48 views

How are individual trees added together in boosted regression tree?

I'm reading Introduction to Statistical Learning, James, G., et al. (2013), in which they describe the Boosted Regression Tree algorithm as following. What I do not understand is Eq 8.10 and 8.11. ...
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111 views

Best machine learning methtod for classificating datasets with non-independent cases within the groups

I have to perform binary classification of my data with supervised machine learning, but I have some difficulties working with my data set. It consists many genetic mutations that have parameters ...
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54 views

AdaBoost over blackbox weak classifier

Can I somehow implement AdaBoost procedure over a weak classifier from another library? For example over SVM from libsvm, or over some neural network. The idea of AdaBoost is that current weights of ...
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131 views

Prediction interval based on cross-validation (CV)

In the text books and youtube lectures I learned a lot about iterative models such as boosting, but I never saw anything about deriving a prediction interval. Cross validation is used for the ...
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70 views

Combining multiple feature subsets through ensemble classification methods?

I have a set of $N$ samples to be classifies in a binary classification problem. I have extracted features from these samples from 4 different perspectives (views) of every samples. Hence I have 4 ...
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What is “fitted function” in the context of boosted regression tree?

I'm following the tutorial of package dismo's boosted regression tree, which produces two graphs, about fitted function and ...
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1answer
18 views

Incremental improvement for boosting

By adding additional factors, will the fitting result of a boosting algo (say Ada boosting) guaranteed to be improved? From my experiment, adding additional factors could make the prediction accuracy ...
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1answer
66 views

Posterior probabilities with decision trees or decision forests

Is there a way to get posterior probabilities $P(C | \vec{x})$ (probability that a data item $\vec{x}$ belong to one of the given classes) in a multiclass classification problem using decision trees ...
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1answer
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For the given type of dataset, what would generally be the set of classifiers that should be tried to get the highest TPR for FPR = 0.01

I'm primarily looking to attain the maximum True Positive Rate for a small False positive Rate of say 0.01. The following is an instance: 1 37.33 228.39 0 77.060599 0.073384 0.052536 ...
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2answers
278 views

Why Adaboost with Decision Trees?

I've been reading a bit on boosting algorithms for classification tasks and Adaboost in particular. I understand that the purpose of Adaboost is to take several "weak learners" and, through a set of ...
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1answer
87 views

How to choose an appropriate maxdepth in rpart.conrol?

I'm using the boosting method in adabag library and trying to choose an appropriate maxdepth in rpart.control for building a 2-class classification model using my training dataset. I have noticed that ...
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70 views

How can I compare GBM feature importances to GBM partial dependence plots?

I am having trouble reconciling the difference between the indicated "importance" from a GBM that I am calculating with what is shown in the partial dependence plots. I would expect higher ...
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58 views

Different variable importance results with stabsel and mboost

I'm using glmboost in the mboost package to fit a boosted regression using linear models as the base learner. There are 13200 observations and about 75 variables, ...
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78 views

Parameter selection for GBM

I'm building a Gradient Boosting model. Given a dataset and event rate, is it possible to get a formula/ definitive strategy for the optimum number of trees, shrinkage parameter and depth of trees? I ...
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20 views

Combining features extracted from different parts of the same image

It is about car identification in images. I have an 64x64 image divided into 16 equal windows. I compute a HoG features algorithm in each one. And I am using the concatenation vector resulted from ...
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17 views

Would knowing the underlying distribution for our data affect how boosting searches for its predictor or how it minimizes the exponential loss?

Assume that the goal of Machine learning is to find a function that is able to minimize the generalization/expected/true error (assuming that the underlying distribution is fixed but unknown): $$E(f) ...
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124 views

Is multicollinearity a problem with gradient boosted trees (i.e. GBM)?

A question about multicollinearity for random forests has been asked and answered, but what about boosted trees?
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140 views

Has anyone publicly shared an implementation of RUSBoost in R?

There's no package available on CRAN, so I was hoping someone in the community had written their own function/package. I see it's been done in MATLAB, so I may just have to start with that and write ...
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32 views

Classifiers that support weighting of the instances

I'm thinking of implementing my own boosting algorithm, so I'm looking for any multiclass classfication algorithms that would support weighting of the examples, i.e. you could specify what examples ...
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48 views

Adaboost for neural networks. Is it still worth it?

I have a question about Adaboost and neural networks. Given the recent development in neural networks (dropout, maxout, or rectified linear units) is there a significant benefit of performing Adaboost ...
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141 views

Adaptive Boosting vs. SVM

I am working on a binary classification case and comparing the performance of different classifiers.Testing the performance of adaboost algorithm (with decision ...
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275 views

Why not always use ensemble learning?

It seems to me that ensemble learning WILL always give better predictive performance than with just a single learning hypothesis. So, why don't we use them all the time? My guess is because of ...
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151 views

Why should all Cross-Validation results be higher than the result on the test dataset?

Sorry, I'm not an expert and my question could be fundamentally wrong. I've read this interesting question because I also was wondering whether to train the model again after cross-validation. Now, ...
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45 views

How to extract the importance of predictors in Adaptive boosting?

I have trained a boosting classifier using ada package in R. Now I want to see the importance of my predictors in constructing ...
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52 views

boosting with ada package. How do I take the most probable answer from predict?

I trained classifier using ada. Now I executed: predict(adaDol,newdata=cords()) and received response: ...
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Is it possible that boosting doesn't increase the predictive power of tree?

I have a data set of 282 observations, and my response variable is a binary variable where 0=normal and 1 =disease. I constructed a classification tree with rpart ...
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74 views

Adaboost and factor variables

My dataset contains both numerical and categorical features like education level, region etc (i use factor variable type for them). I think these variables are important for predicting the outcome of ...
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103 views

BRT analysis using count data

I have some problems with my BRT analysis. Introduction to the data: The dependent variable is count data of a specific palm species in SA, and the predictors consists of nine various kinds of ...
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How to find optimal values for the tuning parameters in boosting trees ?

I realise that there are 3 tuning parameters in the boosting trees model, i.e. the number of trees (number of iterations) shrinkage parameter number of splits (size of each constituent trees) My ...
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123 views

How is L2 Boosting Different from a Big Regression Tree?

I'm learning about boosting. I think I understand how adaptive boosting works for classification. I'm trying to get some intuition for regression boosting. At each iteration, adaptive boosting ...
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28 views

how to generate samples for model selection testing on adaboost

I want to assess some statistical methods for model selection on binary classification using adaBoost. For this, I have to generate artificial samples (input data) and create an oracle that has the ...
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113 views

Values of the weights in Adaboost

I have implemented a simple Adaboost algorithm, using several weak classifiers, and when checking the values computed by it there are alphas with a negative value. Is that possible, or is there a bug ...
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94 views

dealing with exponentials in python - infinities and overflows [duplicate]

In a machine learning algorithm that I'm using, I need to get the exponential values of something in one of the steps. This is the step that I'm dealing with right now: I've already got all the ...
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46 views

Understand the parameters for multiple regression - question based on the notations in a given algorithm

I've set up a regression model but am not sure if I'm doing it right. I'm using multiple regression to help do multi-class classification. So far I feel like I've understood the theory, but I'm ...
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1k views

Boosted decision trees using Matlab

I would like to experiment with classification problems using boosted decision trees using Matlab. In the paper An Empirical Comparison of Supervised Learning Algorithms this technique ranked #1 with ...
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190 views

What does it mean to “fit a regression function” and then use it to update other functions?

Referring to the algorithm on page 11 in this paper on boosting algorithms, I really don't understand step 2, (ii) and (iii). What does this mean: (ii) Fit the regression function $g_j^h (x)$ by ...
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166 views

BRT predictions on zero-inflated gaussian fish abundances include negative results

hopefully someone can point me in the right direction here. I'm using boosted regression trees (BRT) to assess the relative importance of a number of environmental factors (sea bottom temperature, ...
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1answer
3k views

R: What do I see in partial dependence plots of gbm and RandomForest?

Actually, I thought I had understood what one can show a with partial dependence plot, but using a very simple hypothetical example, I got rather puzzled. In the following chunk of code I generate ...
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weighted conditional expectation in adaboost

I'm looking at this paper, http://www.stanford.edu/~hastie/Papers/AdditiveLogisticRegression/alr.pdf around pages 10-11 (marked 346,347 in the pdf). This notation is introduced $$ E_w[g(x,y)|x] := ...