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

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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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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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34 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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15 views

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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56 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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23 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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26 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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17 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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32 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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10 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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14 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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56 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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76 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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27 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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38 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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84 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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1answer
198 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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139 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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27 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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23 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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12 views

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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56 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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64 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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226 views

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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94 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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24 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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1answer
81 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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1answer
73 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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45 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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722 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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169 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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13 views

Boosting in Weka with single PC

Given that I want to run Weka in a single PC, is it a good a idea to use boosting with a three layer feedforward neural network as a base learner? Why or why not? I think boosting requires a lot of ...
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107 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
2k 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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25 views

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] := ...
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76 views

Adaboost: weak learn on different dataset for each iterations

I have seen a few occasion were a weak learner was used iteratively with different dataset. For example, let's say you want to learn to classify {1, -1} according to 3 properties and naive Bayes weak ...
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32 views

Applying ensemble learning to quantile regression?

Is it desirable / possible to apply ensemble learning methods (boosting, bagging, etc) to the quantile regression problem?
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18 views

what does Task in multitask learning mean?

I'm new in multitask learning. I didn't exactly understand what is Tasks in multitask learning ? every task are single training data or what ?
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144 views

Shrinkage parameter in Adaboost?

I'm unclear how the shrinkage parameter works in Adaboost. I understand the concept of shrinkage in the theoretical sense related to ordinary least squares, but I'm not sure how to interpret this ...
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132 views

How Gradient boosting can be more interpretable than CART?

I found this document which compare some learning methods and I don't understand this table : Gradient boosting has a better intepratability score than CART. How is it possible ? I thought gradient ...
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101 views

Gradient boosting algorithm (steps) question

So, far I have read following regarding boosting: Boosting is an ensemble technique. Train learner sequentially, where early learners fit simple models to the data. Analyze data for errors, that ...
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1answer
129 views

C5.0, boosting, and mislabeled data

I'm trying to model a binary classification problem. 5 continuous features, slightly imbalanced dataset (about 60 in one class, a little more than 200 in another). So far I've tried kNN, LDA, and ...
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2k views

Random Forest, is it a boosting algorithm?

Short definition of boosting: Can a set of weak learners create a single strong learner? A weak learner is defined to be a classifier which is only slightly correlated with the true ...
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191 views

Gradient boosting in R uses only a single variable

I am trying to build a boosting model using the package gbm in R. I have the following code: ...
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87 views

Multiple definitions of AdaBoost

The description of AdaBoost in Kevin Murphy's Machine Learning book (shown in a snapshot below) differs from the one in Wikipedia. I am trying to relate both definitions. Step by step, my questions ...
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1answer
617 views

boosting with linear svm

I am working on boosting classifier. I am planning to use linear svm as the weak classifier. I am using liblinear for it. My question is how can I weight each instance of liblinear based on the ...
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524 views

C5.0 Node Decision Tree with Boosting Algorithm (SPSS Modeler)

We are currently looking to mimic the SPSS Modeler's C5.0 Node decision tree model with boosting, which means we'd like to rewrite the whole thing in plain Java. I ...
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1answer
74 views

componentwise boosting based on fisher scoring

componentwise boosting dates back at least to Bühlman and Yu (2003), where in each boosting iteration a set of base-learners (e.g. simple linear models) depending on a subset of the covariates are ...
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58 views

IRLS working weights proportional odds

According to Reduced-rank vector generalized linear models the parameter estimates are obtained by Fisher-scoring algorithm. In the VGAM package the IRLS algorithm ...
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1answer
162 views

Boosting algorithms and overfitting

In the book of Witten and Frank on Data Mining algorithms, I read: "If boosting succeeds in reducing the error on fresh test data, it often does so in a spectacular way. One very surprising finding ...