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

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NLP: How to do feature normalisation for gender classificiation?

NOTE Before I begin, this F-measure is not related to precision and recall, and its title and definition is taken from this paper. I have a feature known as the F-measure, which is used to measure ...
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4 views

Text categorization without labeled data but with fixed categories

I am given a dataset of X articles. I am asked to categorize these articles into a fixed number of C predefined categories. None of the articles is labeled. Just with this information can this task be ...
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20 views

using unlabaled data in a classification problem (There is labeled data but it comes from a biased sample)

I have a binary classification problem. The task is to rank instances from high probability of fraud to low probability of fraud. The following data is available: ~7.000 instances of 0/1 labeled ...
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1answer
74 views

Is there any learning method resistant to the curse of dimensionality?

I have seen a lot of studies and articles explaining the definition of curse of dimensionality and its effects. However, I am curious about if is there any learning method that is resistant to the ...
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7 views

How can we compare two probabilistic models(markov networks) such that its prediction(confidence) depends on amount of training data?

I have a task of comparing two CRF models where each node and edge probability is associated with reliability depending on amount of data it is trained .How can I have a confidence metric for ...
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23 views

Classification of corpus into classes with imbalanced datasets

i am trying to classify some images in classes using the convolutional networks approach. However there are varying numbers of training examples per class. I am worried that that might cause ...
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35 views

Is precision in recommender system related to mean average error (MAE)?

A recommender system is being evaluated while increasing the neighborhood size. The highest precision was achieved between 10-15 neighbors(users) while the lowest MAE was in the range from 30-40 ...
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14 views

evaluate the similarity between two time series

I have two time series, $\mathcal{T}_1$ and $\mathcal{T}_2$, each time series is of two dimensional. One time series is collected from two sensors (SA, SB), and the other is collected from other ...
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33 views

The performance of the classifier went bad after adding extra two features

I'm solving a classification problem using 10 features and logistic regression. The performance of the classifier is fine when I use the 10 features only, however when adding another 2 features, the ...
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13 views

Which classification techniques output a probability that a sample is positive?

For example, logistic regression can predict that a sample will have label 0 or 1. But if you ask R to do a logistic regression, it won't output 0 or 1, it will output a probability that the label is ...
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16 views

Am I fine in implementing Naive Bayes Classifier?

I have implemented one Sentiment Analysis using Naive Bayes Classifier. To do this I have taken the following steps. First I checked the problem, the nature of data (continuous or discrete) and ...
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17 views

Minimizing the misclassification rate

I am reading the book Pattern Recognition and Machine Learning, and have a specific question from a text snippet. I'll state a few lines in the text Suppose that our goal is simply to make as few ...
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54 views

Need pointers to deep learning tutorials

I'm looking for good study material about deep belief networks, with particular emphasis to classification and feature extraction tasks for non-image data. I don't seem to find a great deal about ...
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14 views

What does it mean to say that “a topic is a distribution on words”?

I was taking a machine learning course and they say the following two phrases that confuse me: each document is a distribution on topics. and each topic is a distribution on words. I was ...
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15 views

Can a labeled LDA (Latent Dirichlet Allocation) dataset have just one label per document?

I understand that in labeled LDA, every document should be associated with a set of labels which are known as tagged topics for the respective document. My question is whether a document can be ...
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21 views

predict sales using naive bayes and handle sparse data problem

Problem I am trying to use naive bayes for ranking products in a search application. I would like to predict the sales of a given product given the search keyword and the category. the current formula ...
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9 views

Whats is meant by proximity in random forests?

I came across the term proximity in random forest. But I couldnt understand what it does in random forest. How does it help in classification??
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21 views

Hessian-Free instead of LSTM for Recurrent Net Machine Translation

Last year, Ilya Sutskever and collaborators came out with a paper about a recurrent LSTM net that learns sequence to sequence mappings for machine translation. It's somewhat surprising that the ...
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17 views

How to optimize Gaussian-process parameters for multiple tasks with GPML?

I have a lot of test curves and I want to optimize the length and scale parameters simultaneously for all curves. Is this possible?
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16 views

Relationship between kernel function for distance (locally weighted regression) and kernel function for SVMs?

I am reading Tom Mitchell's Machine Learning. In section 8.2.3, he defines: Kernel function is the function of distance that is used to determine the weight of each training example. In other words, ...
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47 views

Hierarchical clustering, linkage methods and dynamic time warping

My goal is to cluster time series based on their DTW distance. Therefore I've calculated full distance matrices as input for several clustering algorithms. I first had a look at hierarchical methods, ...
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2answers
28 views

Picking cases to label for classification

I'm working on a classification problem with the goal of diagnosing kidney diseases from clinical data. For each patient, we have a large number of observations, and would like to determine whether a ...
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6 views

Sample complexity for agnostic PAC learning for real valued functions

How many samples are needed for ERM to have $\epsilon$ excess risk relative to the best hypthosis $h^*$? Assume a bounded (and Lipschitz, if needed) loss function. The only survey I have been able to ...
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67 views

What is the difference between feature selection and dimensionality reduction?

I know that both feature selection and dimensionality reduction aim towards reducing the number of features in the original set of features. What is the exact difference between the two if we are ...
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33 views

Does the recurrent neural network require the length of input samples all the same

Theoretically, the training of RNN doesn't require that the samples must have the same time length, but it seems to me that some software or open-source requires that the input data has the same time ...
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31 views

Least-square fit with uneven distribution of data

I'd like to perform least-squares fit to data which is unevenly distributed on the x-axis. For example, if I was to bin the data, it would be something like x = 0~5: 10 data points x = 5~10: 20 ...
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1answer
20 views

Correlated cases and Cross Validation

I'm posting to ask if there is a method of cross-validation for correllated data that is already well implemented in R language. Some quick search on such method shows some techniques like h-block ...
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26 views

What is the advantage of non-negativity in matrix factorization?

I am wondering why matrix factorization techniques in the machine learning domain almost always expect the provided matrix to be non-negative. What is the advantage of this constraint? Background: I ...
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15 views

How do I determine the minimum sample size needed to evaluate the performance of a binary classifier with a statistically significant result?

I’m trying to determine the minimum sample size(s) needed to evaluate the performance of a binary classifier with a statistically significant result. I'm not trying to compare different classifiers ...
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3answers
99 views

What is the straightest line I can make using a linear combination of time series

I have 3 processes which generate an output in the form of a time series. I want to choose a linear combination of the processes that will result in the straightest line possible (I think this ...
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12 views

How to find the probalities of a,b,c (mutually exclusive events) when i turn the problem into three binary classification problems?

I am using scikits linear logisitc regression to classify three events a,b and c. it works better (score) when i convert them into a binary classification model. such as: 1. M1 classifies a or b 2. ...
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9 views

Personalization, user-adaptive and recommender systems

I am currently undergoing research into the field of systems that adapt content and layout depending on how the user uses the application. I am however puzzled as to the following terms as they are ...
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2answers
52 views

Data partitioning according two variables

I am working with the following dataset: ...
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28 views

Should I use epochs > 1 when training data is unlimited?

If I have virtually endless training data (it's synthesized) is there still purpose in having epochs? I.e. training on the same samples multiple times?
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30 views

Popular named entity resolution software

I am working on a project and need to extract persons' names from a large amount of documents. This task should belong to the named entity resolution problem. What are currently some of the most ...
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7 views

Estimating the covariance matrix in LDA ESL

I am reading Elements of Statistical Learning on LDA. On page 109, it talks about how we need to estimate parameters for Gaussian distribution. But why do we use this estimate for the covariance ...
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32 views

Concept of Hopfield Networks

Just want to double check my understanding of comcept of Hopfield networks. would a trained hopfield network have an energy function that has local minimas equal to the number of the training ...
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2answers
94 views

How to understand that MLE of Variance is biased in a Gaussian distribution?

I'm reading PRML and I don't understand the picture. Could you please give some hints to understand the picture and why the MLE of variance in a Gaussian distribution is biased? formula 1.55: $$ ...
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2answers
53 views

Odds vs. Probabilities (Confusion)

In logistic regression, I know that Odds and Probabilities are two different things, but still I can't distinguish the difference between them. I will be very grateful with your clarifications.
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18 views

Handling sparse document term matrix

I am working with a corpus of several thousand documents (41,732) however the documents tend to be short (the median number of terms per document is 3) resulting in a sparse document term matrix. ...
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11 views

To interpret SVM's probability output in text analysis

So, my question is about the application of the SVM's (or naive Bayes') probability output (via Platt's scaling). I know the interpretation of the output is the probability of a given observation ...
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16 views

How to Format Data for Structured Learning Problem?

I'm working on a project classifying discussion forum posts into various pre-defined categories, and would like to use a sequential learning model such as CRF's. I code mostly in Python and have found ...
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33 views

analysis of bank account record

I am new to the field of time series analysis, but I would like to have a look at my bank account and determine my spending habits. I read a lot about clustering of multiple time series but I think I ...
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30 views

What do these decision boundaries indicate in random forest and svm?

I was working on data science harvard homework problem. It is a two class classification problem in which they plot the decision boundary for random forest, svm and decision tree. The problem has 2 ...
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47 views

Are visualization techniques useful when the predictive model is a highly flexible machine learning algorithm?

I’ve always used highly flexible machine learning algorithms like boosted trees, support vector machines, and random forests that supposedly excel at identifying non-linear and irregular patterns and ...
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1answer
24 views

Understanding the effect of hyperparameters in machine learning experiments

In machine learning every algorithm has a set of hyperparameters which needs to be optimized for best prediction performance. The simplest method for this optimization is called grid search which ...
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1answer
41 views

Conditional distribution for Exponential family

We have a random variable $X$ that belongs to the exponential family with p.d.f. $$ P_X(x|\boldsymbol \theta) = h(x) \exp\left(\eta({\boldsymbol \theta}) . T(x) - A({\boldsymbol \theta}) \right) $$ ...
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39 views

determining how “important” a feature is in predicting a target in decision trees

Random forests allow us to compute a heuristic for determining how "important" a feature is in predicting a target. This heuristic measures the change in prediction accuracy if we take a given ...
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31 views

In developing a personal assistant, what is the best classification machine learning algorithm to use? [closed]

I've been developing a personal assistant-type program (siri-esque, I guess), which currently uses regexes loosely matching text to infer the requested operation, but as you can imagine, as it grows, ...
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44 views

Any machine Learning models to predict dates?

I have a general question regarding machine learning models. The idea is to predict what DATE the customer is likely to make transactions or purchases. Variables present in the data set are item, ...