Methods and principles of building "computer systems that automatically improve with experience."

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Model instability in data mining. When it is big enough to discredit a model and how to measure it?

Let's say I have two models. One has cumulative lift on test data 4.322578, second 2.84488. The only advantage of the second over the first consists in the quality of having the cumulative lift curve ...
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27 views

Choice of an evaluation metric for a graph clustering algorithm

I have instances for which the only thing I know is 70% of the distance matrix. I know some of these points form groups of correlated points (each point of a group is "close" to every point of the ...
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40 views

Machine Learning : Classification algorithm for very high dimensional data which is uniquely definable in a very small sub-space

I am new to machine learning, so forgive me if i am doing something absolutely absurd. I have a classification task (~100 classes) and have about 2 million training data points in a 2000 dimensional ...
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1answer
33 views

gaussian mixture model - approximate a matrix

I have a similarity matrix M - the value M(i,j) indicates the similarity between two elements i and j. I want to approximate that matrix using a Gaussian Mixture model or I want to cluster that ...
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2answers
139 views

Using the gap statistic to compare algorithms

I want to compare the performances of two clustering algorithms that give me different numbers of clusters. I recently learned about the gap statistic. However, from what I have learned, this ...
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78 views

How to report a SVM model to a 3rd party after cross-validation?

I have a binary classification problem. I trained my dataset using a Support Vector Machine (SVM). Now I want to report the model I trained to a 3rd party so that they can use. For the primal probem ...
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20 views

difference between text classification and categorization

Could any one help me to clarify the exact difference between text classification and text categorization in machine learning point of view. Thanks
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40 views

General questions regarding text-classification

I'm new to Topic Models, Classification, etc… now I'm already a while doing a project and read a lot of research papers. My dataset consists out of short messages that are human-labeled. This is what ...
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319 views

Can machine learning find all sort of crazy connections?

If you try a real thoroughly won't a computer find all sort of silly patterns? Messages from ETs in the bible rainy Sundays in China or Australia -> the chances of your sport team win reading many ...
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31 views

Which algorithmic approach is best for this problem

I have a problem where I get data from 3 different sources s1, s2, s3, and I have the target (value). I might have missing values from some of the predictor variables at certain rows. This is the ...
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103 views

Maximize sum of f(x), where f(x) is unknown, but we learn as each x is chosen

Let's suppose that I have a function like below, but I don't know what it is. However, as I choose x, I know what corresponding ...
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62 views

Journals in statistical learning / machine learning [closed]

Can you please name some major and minor journals publishing articles in the field of statistical learning / machine learning. regards Anthony
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24 views

Word Sense Disambiguation in Practice

I have a question that might seem very obvious but I don't really have a good answer for it. There are many algorithms out there that deal with word sense disambiguation but all of the ones that I ...
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45 views

Machine Learning with Skewed Classes in R

I am looking for some suggestions on what methods are appropriate for training a dataset with a high skew in the outcome classes. The ratio of Class 0: Class 1 is about 20:1 and I am looking to ...
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30 views

Which diffusion of latent Dirichlet allocation is helpful for assign the words corresponds to each topic?

In my corpus documents I have two different subjects. Which diffusion of LDA (asymmetric or symmetric) could help for assigning the words corresponds to Subject 1 and Subject 2 in my Topics? Here is ...
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86 views

Will Multivariate Gaussian classifier work for text classification?

So far i have evaluated mn Bayes and Bernoulli, so my question is if i take the counts of the words of each document and use them for assigning the document to the particular class will it work with ...
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1answer
29 views

Classifier weighted towards recall?

I have a classification problem where getting true positives is much more important than true negatives. To be clear, I know that roughly 10% of my population are actual positives, but I can assign ...
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18 views

What is the difference between the metric window width and Nearest-neighbor's window in Kernel Smoothing methods?

I'm learning Kernel smoothing methods. I didn't really get the difference between the metric window width and Nearest-neighbor's window. For me both seem the same. Can anybody explain it to me? for ...
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1answer
39 views

How to define silhouette for one cluster?

I want to compare two clustering algorithms. I took data that the first algorithm gathered in one cluster. The second algorithm gave 3 clusters for the same points. In order to compare the results, I ...
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2answers
121 views

k folds cross validation on a multi-class dataset

Cross validation is one of the most important tools because it gives us an honest assessment of the true accuracy of our system. In other words, the cross-validation process provides a much more ...
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3answers
91 views

Scalability of Markov Clustering

I want to do graph clustering on a large dataset (A graph with 600,000 Nodes and tens of millions of edges). I read about Markov clustering. I saw this algorithm involved the calculation of a ...
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1answer
42 views

k-medoids algorithm with incomplete distance matrix

I want to apply k-medoids algorithm using an incomplete distance matrix as input. How can I handle the lack of information of this matrix? Just ignoring the missing distances? Or is there a better ...
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1answer
34 views

k-core clustering algorithm

I am trying to cluster data. Each point in this dataset is connected to some other points. I want to define clusters "depending on how much the points are connected to each other". After some ...
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14 views

What is the latent class in pLSA

I want to implement Probabilistic Latent Semantic Analysis(pLSA) in Python. I have searched many times but couldn't find a simple tutorial. ...
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31 views

What can be a cause of a extremely high standard coefficient?

I am using RapidMiner to perform linear regression with ridge parameter 1$\text{E}$ -8, min tolerance 0.05 and M5 prime for feature elimination. The std coefficient ...
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21 views

Correlating ranked lists

Let's assume I have 10 users who rank a list by preference. A B C etc. My questions are: What is the best statistical method to find which lists are the most correlated? If they are the same, ...
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1answer
54 views

How to set the step size for stochastic gradient descent such that its provable it will converge

Recall stochastic gradient descent (for regression): $\theta = 0 $ $ \text{Randomly select } t \in [1,n]\{\\ \quad \theta^{(k+1)} = \theta^{k} + \eta_{k}(y^{(t)} - \theta \cdot x^{(t)})x^{(t)}\\ ...
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1answer
80 views

Linear regression closed form solution and having enough training points

I was trying to understand better when we can learn a unique parameter for linear regression and how much data is required to get one. Say that we want to learn a parameter $\theta$ such that ...
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36 views

Machine learning with ordered labels

The usual method for adapting binary classifiers like various SVMs to multilabel data is one-vs-all, which assumes that labels are independent and in case of a prediction error we don't care what ...
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33 views

Random initialization with k-means clustering

I read on my machine learning course (on coursera) that random initialization performed several times and then taking the cluster with the lowest cose could help when the number of clusters is ...
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25 views

Test data has maximum number of unseen nGrams and prediction is failing

I have built a Machine learning model for twitter sentiment analysis. I have followed following steps to build my final model. Model Creation: collected uni-bi-tri grams from entire training data ...
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30 views

What does the term “Estimation error” mean?

I was reading some notes on machine learning when I came across the following sentence: First, we may have a large estimation error. This means that, even if the true relationship between x and ...
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1answer
64 views

Do fewer support vectors imply a simpler model?

I am applying $\epsilon$- and $\nu$-regression to sample data, and I discovered I had different results in terms of the count of support vectors. When I have fewer support vectors, does it mean that ...
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26 views

Evaluate collisions in classification problems

Short Introduction In a classification problem, the objective is to identify to which of a set of categories a new observation belongs, on the basis of a set of examples whose category membership is ...
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3answers
89 views

Performing PCA with only a distance matrix

I want to cluster a massive dataset for which I have only the pairwise distances. I implemented a k-medoids algorithm, but it's taking too long to run so I would like to start by reducing the ...
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58 views

Evaluating a regression model's performance using training and test sets?

I often hear about evaluating a classification model's performance by holding out the test set and training a model on the training set. Then creating 2 vectors, one for the predicted values and one ...
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1answer
112 views

Multidimensional scaling using Python

I have 6,000 points for which I have all pairwise distances in a distance matrix. I want to get an idea whether these data were generated by a mixture of Gaussian distributions so I'm trying to get a ...
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35 views

How to extract structured information from a text string?

I have a text string containing unstructured data and I would like to analyze it in order to extract structured information. In particular, this text string specifies when a service is operational ...
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1answer
155 views

Beginner - How can I use ranked values in my Logistic Regression?

I am running a Logistic Regression on some data to predict if a webpage is "good" or "bad". I got the dataset from a finished Kaggle competiton here (train.tsv). I extract the second column of this ...
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37 views

Scaling the backward variable in HMM Baum-Welch

I am just trying to implement the scaled Baum-Welch algorithm and I have run into a problem where my backward variables, after scaling, are over the value of 1. Is this normal? After all, ...
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3answers
94 views

Examples of machine learning in personal computers [closed]

Are there any examples of machine learning in our PC's? The only one that I know is Windows Speech Recognition application. I do not mean any add-ons. I mean any basic applications that are ...
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1answer
46 views

Divergence measure of two classifiers' performance?

I have two classifiers built with the same data. How can I measure divergence of these models? I found something like DIC but I don't know how to calculate this in R?
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2answers
76 views

Example how maximizing and minimizing a function can be equivalent?

I don't understand how sometimes given an optimization problem, a function could get its optimal solution by minimizing or sometimes just by reformulation it becomes maximizing. Can you please give me ...
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1answer
44 views

Minimizing the norm of a vector of parameters

I'm reading a paper that defines a function $f_w(x)$ that takes input $x$ and parameters $w$ and a set of constraints. There are also training data. The aim is to find the set of parameters $w$ that ...
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1answer
44 views

Goldfarb Idnani quadratic solver

I am implementing the Support Vector Regression (SVR) algorithm by means of quadratic programming. In order to do that, I am using an optimization library that contains a quadratic solver based on the ...
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1answer
73 views

Evaluation of probabilistic predictions

In the 2010 KDD cup, participants were tasked with estimating the probability that a student would solve a particular exam question. The competition winner was whoever produced the lowest root square ...
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32 views

Which loss function for?

I want to model some data with a "Boosted Regression Trees" in order to do so I have to define a "loss function". As a response variable I have count data. So I assume that a "poisson distribution". ...
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1answer
44 views

Simple question about multivariate/multiclass classification

From this link Text Classification using Naive Bayes, there are two models described for classification, Naive and Bernoulli. My question is if i want to make this classifiers for multiclass ...
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32 views

Machine learning - Weighting the regularisation function

I am working on a machine-learning algorithm for estimating the performance of a student on various tasks. I'm using logistic regression with a L2 regularisation parameter. One parameter we used was a ...
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1answer
35 views

What does “aspect model” refer to in machine learning

Hopefully this is the right place to ask my question. I am reading this paper about cold-start recommendations: http://dl.acm.org/citation.cfm?id=1352837 the expression "aspect model" is used a lot ...