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

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Intuition behind sparsity in over-complete sparse auto-encoders

I am trying to get a grasp of the intuition behind the sparse representation used in over-complete auto-encoders. One piece of text that offers a somewhat intuitive explanation is from ...
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6 views

Interpreting the lift curve

Suppose we have two classes: A and B. Suppose we use a logistic regression to assign each unit to A or B. The curve lift is calculated through this formula: $\frac{n_{22}/n_{.2}}{n_{2.}/n_{..}}$ ...
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1answer
9 views

Is there a version of Latent Class Analysis with unspecified # of clusters

I understand that you can use the elbow method to plot LCA solutions vs log likelihood to figure out, at which k, it is no longer worth it to add more clusters. And I will resort to this if need be. ...
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7 views

LSTM end of input sign required?

I am coding an LSTM module. In non-linear input like one-hot-encoded words, you use an extra sign (like <eol>) at the end of the series before zero-padding to ...
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12 views

Measuring effectiveness of marketing through attribution analysis

My data(dataframe in R) looks like this:The data is ordered by CustomerName and then TimeofEvent. ...
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1answer
26 views

Predicting the job switching period of an employee

I have a machine learning problem to solve. Given the data about employees, is there a way by which we could possibly predict that when an employee is going to switch his current job? We can make use ...
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1answer
32 views

Is building training data set from unlabeled data considered as a scientific contribution? [on hold]

Is building a training data set, from unlabeled data, for a machine learning classifier considered as a scientific contribution?
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17 views

What are the differences between autoencoder and t-SNE?

As far as I know, both autoencoder and t-SNE are used for nonlinear dimension reduction. What are the differences between them and why should I use one versus another? thanks!
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2answers
97 views

What is bucketization?

I've been going around to find a clear explanation of "bucketization" in machine learning with no luck. What I understand so far is that bucketization is similar to quantization in digital signal ...
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1answer
25 views

GridSearchCV Regression vs Linear Regression vs Stats.model OLS

I am trying to build multiple linear regression model with 3 different method and I am getting different results for each one. I think that I have to get the same results but ...
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0answers
11 views

Standardization for regularized, sparse hashed logistic regression

As the question states, I'm fitting large, sparse logistic regressions (with hashed interactions, a la vowpal wabbit) for a machine learning system. The features are on different scales, and I'm a ...
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0answers
29 views

Markov decision process in R for a song suggestion software?

We have a music player that has different playlists and automatically suggests songs from the current playlist I'm in. What I want the program to learn is, that if I skip the song, it should decrease ...
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1answer
65 views

Bag-of-Words for Text Classification: Why not just use word frequencies instead of TFIDF?

A common approach to text classification is to train a classifier off of a 'bag-of-words'. The user takes the text to be classified and counts the frequencies of the words in each object, followed by ...
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25 views

Variance of binomial vs. multinomial distribution in cross-validation

Suppose we have a dataset with $N=100$ observations. We do $K$-fold cross-validation with $K=10$ and $K=100$. In the first case, the classification decisions are sampled (can I say it like this?) ...
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1answer
20 views

ROC and constant factor on probabilities

I play around with a few data to learn and I am wondering about something; I can evaluate my results with ROC which is processed from FP and FN. I had predicted a few probabilities for my events to ...
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39 views

Finding algorithm to detect anomaly in non gaussian data

I have a data (time series like CPU, traffic and so on) that doesnt have a normal distribution usually (especially when I'm looking at 1 hour data). Are there any algorithm to find anomalies? I ...
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1answer
45 views

Why the majority of serious machine learners are from the computer vision society? [on hold]

I have noticed that most individuals who want to specialize in machine learning tend to go into computer vision labs. I was always curious about why computer vision in particular. My confusion was ...
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1answer
45 views

Text analysis : What after term-document matrix?

I am trying to build predictive models from text data. I built document-term matrix from the text data (unigram and bigram) and built different types of models on that (like svm, random forest, ...
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1answer
37 views

Predict user behaviour with constantly changing input variables

How to work on building an engine for a website wherein we want to score/recommend stuff based on her different activities, like the music she rated or the article she read, or whether email ...
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14 views

R: How to choose the height parameter in cutree, or: how to find the optimal number of clusters in UPGMA clustering?

I am using hclust() to carry out a UPGMA clustering (method="average") in R. Then, I'm using ...
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18 views

Rank Deficiency?

What can I do about rank deficiency? Can I just ignore it? I have an unbalanced dataset and using logistic regression (caret glm). I get 50 errors saying that my data is rank deficient and the results ...
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13 views

Search terms and Semantics [on hold]

Suppose I type apple and get the following list of results: ...
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0answers
16 views

Describing the distribution of N points in D-dimensional space?

I want to tackle a classification problem by describing the samples as its descriptors' distributions. So let's say each sample has a label, and $N$ vectors of dimension $D$, (N and D are fixed) and ...
2
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1answer
79 views

How do you use test data set after Cross-validation

In some lectures and tutorials they suggest to split your data in three parts: training, validation and test. But it is not clear how test data set should be used and how this approach is better than ...
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3answers
244 views

How to intuitively explain what a kernel is?

Many machine learning classifiers (e.g. support vector machines) allow one to specify a kernel. What would be an intuitive way of explaining what a kernel is? One aspect I have been thinking of is ...
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15 views

machine learning for a ontology classification problem

I am working on a ontology based classification problem.The main objective was: computing ontology has keywords related to different categories.Each category talks about the domain it is related.For ...
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0answers
25 views

Limitations of ensemble selection from libraries

Question related to the approach in Caruana's paper: "Ensemble Selection from Libraries of Models" (linked below) http://www.cs.cornell.edu/~caruana/ctp/ct.papers/caruana.icml04.icdm06long.pdf Seems ...
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19 views

CTR Enhancement Model

I am looking to build a model to enhance CTR. Below is the business description. We have a coupon based website. For each retailer, we have a retailer page. Each retailer page will have up-to 100 ...
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10 views

how to calculate the number of parameter (no zero parameter) in an matrix in matlab I give the model_matrix [on hold]

fonction nmbrerparameter=model_matrix c=0 for i=1:10 for j=1:10 if c~0 size(model_matrix.trans) size(mode_matrix.mix) end end end
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28 views

Which unsupervised learning method should I use on classification on many point cloud datasets?

I have a few abstract and high dimensional point clouds in the form of distance matrices. I want to do unsupervised learning on this dataset. The problem is, I am not using one distance matrix, but ...
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18 views

Why is linear svm solver faster than nonlinear solver?

Both linear and non linear SVM solve can be solved using primal or dual problem. Why is linear svm solver faster than nonlinear solver?
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2answers
56 views

How to Balance my Dataset?

I have 90% negative examples and 10% positive examples,(13,000 observations, 90 Variables). my model shows me that the miss classifications error is 0.1 but my confusion matrix shows me that the TP ...
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2answers
66 views

Is chi-squared valid in this scenario?

I'd like to know whether I am misusing Pearson's chi-squared test. And if so, what should I be doing instead. I've a game-playing program, a "bot", for a zero-sum two-player game. To improve it, many ...
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11 views

Reducing model weight increases accuracy

I have a question. Say i have 3 class labels 1,2,3 Basically, i have about 1 million examples of 1, 1000 examples of 2 and 3 each. Hence, the weight of my label 1 would be 0.001, 2 would be 1 and ...
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20 views

Carry out a 2-Sample t-test whether the means of two independent groups differ

I have carried out a paired t-test on the labor.arff data set and found out that one classification is not statistically better suited for this data set than the other. This is represented by the ...
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11 views

Changing the class file from nominal to numeric in order to carry out the linear regression [on hold]

I am trying to perform the LinearRegression classification on the diabetes.arff and glass.arff data sets, with little luck. The option is greyed out and I cannot ...
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5answers
271 views

What algorithm should I use to detect anomalies on time-series?

Background I'm working in Network Operations Center, we monitor computer systems and their performance. One of the key metrics to monitor is a number of visitors\customers currently connected to our ...
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0answers
21 views

Bound on the total change using Pearson's r

I am given an increasing series $(x_1,....x_n)$ and I know the pearson correlation between $(x_1,....x_n)$ and some (unknown) increasing series $(y_1,....y_n)$. Can I derive an upper and a lower ...
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12 views

Interpret F values of selected features

I have a dataset that contains wines and their ratings. An entry contains the name of the wine, the grapes used, the year and the rating: 'Chateau Pape', 'Pinot Gris', '1983', 93.4 I'm interested in ...
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1answer
84 views

What should be my training set for a word-spotting program?

I wanted to create a simple voice recognition program. It should be able to distinguish my voice from other sounds. Aside from my voice, what should I add to my training set? Also, I want to extend my ...
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34 views

How to report machine learning research?

I am using support vector machines and cross-validation for a binary classification task. I have constructed three different models, and therefore I have three sets of results. How should I report the ...
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22 views

Feature selection of non stationary data

I am working with EEG signals which are non-stationary. I have used spectrogram to analyse the data in specific frequecies. I have to select some features from the specific-frequency time signals ...
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13 views

Longer forecasting with one-step-ahead model

It is totally a noob question but I cannot find any explanation on the subject. Suppose I build a forecasting system for time series $x$, using as inputs $[x_{t-n},...,x_t]$ to predict the next ...
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2answers
42 views

Will decision trees perform splitting of nodes by converting categorical values to numerical in practice?

In Decision trees, while doing classification or regression, are we using only numerical values. Suppose if i am having a column of 'Wind' as a feature. Suppose, I am having 5 rows ( observations ). ...
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16 views

Minimum training sample size for a hierarchical hidden semi-Markov Model (HHSMM) [closed]

I've implemented a HHSMM machinery but I have doubts about the minimum size of training set that I have to acquire for the experiment. Any method?
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1answer
36 views

Does rank of observation matrix tell anything useful when applying machine learning?

Suppose I have an observation matrix of size $N \times M$ where $N$ is the number of samples and $M$ is the number of variables. If the rank of the observation matrix is $R<M$, does it tell ...
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1answer
8 views

GPML producing wrong output using correct target labels

I am using the GPML code found here. The key function in the aforementioned library is the gp function described below: Two modes are possible: training or ...
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0answers
66 views

Error in linear regression

Given two series $(x_1,...x_n)$ and $(y_1,...y_n)$, and assume that we know $x_{n+1}$. Given the fact that the pearson correlation won't change in the next observation of $y_{n+1}$, can we bound the ...
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20 views

Difference between Latent and Explicit Semantic Analysis

I'm trying to analyse the paper ''Computing Semantic Relatedness using Wikipedia-based Explicit Semantic Analysis''. One component of the system described therein that I'm currently grappling with ...
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37 views

Forecasting values based on day of week and hour

Disclaimer: Not really good at statistics. Scenario: I have some data, sampled by the hour. I want to make some forecasts taking into consideration that the data seems to be influenced by the day of ...