Methods and principles of building "computer systems that automatically improve with experience."
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0answers
75 views
Description of all models in R's caret package? [closed]
I've been looking into machine learning recently, mostly using R. I just came across the caret package and it seems to be brilliant for quickly trying out different models. It seems a great tool for ...
1
vote
1answer
61 views
Derivation of the posterior over topics in LDA
When studying the latent Dirichlet allocation, I am not very clear about some procedures in their deriving equations. Please refer to the attached figure, how to understand those two steps, marked as ...
0
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2answers
43 views
difference in training and testing procedure of model
Can anyone please tell me the difference in training and testing of a model. I have developed 5/6 different single pass online learning algorithm (ets, ets+, evolving fuzzy modelling, SOFNN, ...
3
votes
1answer
78 views
Decision tree : handle attribute with many nominal values
I would like to build a decision tree from a training data. I have an attribute with many nominal values. For example, the department name attribute has about 20-30 values. I would like to group ...
0
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0answers
81 views
How to compute precision for a multiclass problem?
I have a question about calculating precision on a multiclass problem. If the true positives of some actual class is 0, and its false negatives is also 0, then how to calculate its recall? In this ...
0
votes
0answers
81 views
Predicting twitter activity using time series analysis
I'm interested to build a model for predicting how many tweets people I follow will probably tweet today (or by hour), based on their previous tweets in the last 60 days (or more).
Of course that the ...
1
vote
1answer
59 views
Non-independence of IVs in a random forest model
How is a random forest model affected if some of the variables are not independent?
0
votes
1answer
89 views
Choosing a better data-set
I have two data-sets for same samples. But they are produced using two different instruments. I want to choose one data-set for further analysis. How can I find/prove which data-set is better?
To ...
3
votes
0answers
85 views
Using priors to detect an effect? logistic Bayesian regression
I have designed an idea and am looking for similar approaches in other literature/areas or if I have applied the Bayesian concepts wrongly. Here is a statement of my problem:
I am modeling the ...
0
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0answers
37 views
Form field identification
I am working on a problem in which given a form (mostly scanned) one needs to automatically detect all the fields and their corresponding values from it. The information that I have is location of ...
2
votes
1answer
123 views
Using the appropriate machine learning algorithm
I am not sure if this is the right forum to ask this.
I have some data of the houses, like their size(in square meters), if they use aircondition, how many residents live in, I have their electricity ...
1
vote
1answer
115 views
what should be the parametric form of the l2 regularization in a Bayesian setting?
In a Bayesian setting for parameter estimation, what should be the parametric form of the prior distribution in order to perform l2 regularization?
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0answers
162 views
How helpful is a quant job in Goldman Sachs for later PhD in Machine Learning?
I am a masters in Computer Science and am interested in pursuing a career in Machine Learning, possibly academic, in the long run.
I have been offered a position related to Financial Modelling at ...
2
votes
0answers
72 views
Random Forest or other machine learning techniques with paired samples
I am trying to select features from paired samples and was wondering if there are methods out there that adapt random Forest or other machine learning algorithms to paired samples i.e. if randomForest ...
0
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0answers
41 views
May I get HMM calculations Checked?
I was trying to understand Hidden Markov Model(HMM). I was working out some examples.
The first work out was on initial probability, transition probability and emission probability.
I was trying to ...
0
votes
3answers
162 views
Binary classification machine learning
I have
data set (30,000) mapping people to incomes(<=some number ,>some number)
each instance has 15 features so as age, education.
I would like some advice/pointers as to the best machine ...
1
vote
4answers
152 views
Neural networks for simplistic image classification
I want to train a neural network to classify a few simple, cartoony images like the ones below (for the moment I only have the classes house, tree, and sword).
The images I am (currently) using ...
2
votes
1answer
41 views
How can I estimate a score for my users, on if they will match ad campaign criteria?
I have ad campaigns that I want to display to users. Each one has criteria a user must meet in order for them to be valid for the campaign. For example, "User must be in the USA", or "User must like ...
0
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0answers
44 views
Online Linear Regression with updates on past information
Suppose we have the following algorithm
An online linear regression algorithm implemented using gradient descent. The step rate $\alpha$ is calculated using something that correlates to the squared ...
0
votes
0answers
49 views
Are my HMM calculations going fine? [closed]
I was trying to understand the hidden Markov model (HMM) and to do some calculations, and I got some doubts. I attach my study in this Google Drive File.
Can you check if my calculations are fine?
I ...
1
vote
1answer
42 views
Inconsistency in cross-validation results
I have a set of dataset recorded from subjects as they perform some particular cognitive task. The data consists of 16 channels and a number of sample points per channel and I want to classify this ...
0
votes
0answers
23 views
Classifying foreground vs background for ellipse shapes
I have images of ellipse shapes which are read in as a matrix of pixel intensities. I'd like a way to be able to classify whether a pixel is foreground (belonging to ellipse) or background (not ...
0
votes
0answers
43 views
How to solve a dilemma case on Support Vector Machine?
I am learning the SVM classification and especially interested in applying to medical data. Now, I encounter a problem and do not know if this dilemma has a terminology for it.
Assume that there ...
3
votes
1answer
97 views
Graphical representation of cross-validation errors for regression
What are some good ways of presenting/comparing cross-validated RMSE errors for regression using various models, graphically via plots? As of now, I have been presenting the quantitative results in ...
0
votes
1answer
53 views
liblinear one vs rest learn parameters
Liblinear (http://www.csie.ntu.edu.tw/~cjlin/liblinear/) does not support for probability estimates.
Say I have three classes C1, C2 and C3. I want to learn the model paramters for each 'one vs rest' ...
1
vote
1answer
36 views
Generating rules to obtain a given categorical distribution… is it possible?
I'm working on a problem, I was wondering if there are any methods available to do the following.
I have a data set with information on people (continuous and categorical data). I have 3 categories ...
1
vote
0answers
85 views
Weighted covariance matrix using kernels
I would like to create a weighted covariance matrix (say 5 variables) using 3 different time points where the weights come from a kernel function (can be normal, triangular, etc) but I'm not ...
0
votes
0answers
30 views
Is there a theoretical basis for the shrinkage used in Boosted Regression Trees?
In Gradient Boosted Regression Trees, a shrinkage $\nu$ is often applied as:
$$ f_t(x) \leftarrow f_{t-1}(x) + \nu h(x)$$
where $h$ is the regression tree learned by fitting the tree to the gradient. ...
4
votes
2answers
538 views
how to calculate precision and recall for multiclass classification using confusion matrix?
all, I wonder how to compute the precision and recall using confusion matrix for multi-class classification problem. In specific, one data can only be assigned with most probable class/label.
I like ...
3
votes
1answer
221 views
What is the difference between a neural network and a deep belief network?
I am getting the impression that when people are referring to a 'deep belief' network that this is basically a neural network but very large. Is this correct or does a deep belief network also imply ...
2
votes
0answers
47 views
Some examples of errors in ESL?
I am reading the book The Elements of Statistical Learning (Hastie et al, chapter 7) and I am confused about the different kinds of errors mentioned in the book
Test error $$Err_\tau=E(L(y, ...
0
votes
1answer
114 views
Pocket algorithm for training perceptrons
When you read about perceptron variants at Wikipedia there is explained an algorithm: Pocket Algorithm It is said that:
solves the stability problem of perceptron learning by keeping the best ...
1
vote
2answers
118 views
Data whitening for improving regression
My Data: $X_i= \{0.4;~7;~1,000;0;~0.8;~1;~0;~40;~0.7;~1;~0;~89,100\},~Y_i=345$ The training set size is $\approx35, 000$. $Y$ is the dependent variable and the task is to estimate its value ...
1
vote
0answers
177 views
Machine Learning Algorithms vs. Linear Regression
Do machine learning algorithms like Boosted Regression Trees (in the R package (gbm)) follow the same statistical assumptions of not including correlated predictor variables in GLM?
i.e. If I have ...
0
votes
0answers
53 views
Forming training set for Multinomial Naive Bayes
Is it true that Multinomial Naive Bayes requires equally by count training data for each class to get best performance?
For example, we forming classifier for three classes - Japan, China, Korea.
...
0
votes
0answers
105 views
Bootstrapping Methodology
I have this bootstrap setting:
Given $n$ vector-valued statistics (each statistic is a vector) of dimension $r \times 1$, I generated $1000$ bootstrap samples and then generated an estimate of each ...
0
votes
0answers
60 views
Finding the projection used in multidimensional scaling
Background
I have a set of data points in high-dimensional (512D) space that I wish to map to 2D for visualisation. I am interested in observing in 2D the (approximate) relative distances between the ...
1
vote
1answer
103 views
Building the dataset for Random Forest training procedure
I should use the bagging (bootstrap aggregating) technique in order to train a random forest classifier. I read here the description of this learning technique, but I have not figured out how I ...
1
vote
2answers
117 views
What are the state of the art methods for person segmentation and person pose identification
I have tried asking this on another forum, but after 4 months there are no posted answers, so I am asking it here:
What is the current state of the art approach for determining the pose of a person ...
1
vote
1answer
48 views
Independence assumption in maximum entropy models in NLP
I am reading Klein and Manning's notes on Maximum Entropy for Natural Language Processing. On slide 22, they have an equation saying,
$P(C|D,\lambda) = \Pi _{(c,d)\in (C,D)} P(c|d,\lambda)$. I am not ...
0
votes
0answers
116 views
Kaggle - Don't Get Kicked Competition [closed]
I would like to use dataset from Kaggle's competition Don't Get Kicked for my analysis. However I have problem with ...
1
vote
0answers
50 views
Choosing a multiclass strategy
What would be the best approach to choosing the multi-class strategy (MSVM, OVA, ECOC) for classifying a large number of classes with limited examples of each class?
Another two factors that define ...
2
votes
1answer
164 views
Simple text classifier: classification taking forever?
I work for a small tech startup, and I want to classify or users into demographics based on the domain of their email address. When users sign up to our site, they can enter a job category, or pick ...
3
votes
0answers
150 views
Statistics for machine learning, papers to start?
I have a background in computer programming and elementary number theory, but no real statistics training, and have recently "discovered" that the amazing world of a whole range of techniques is ...
0
votes
0answers
61 views
Examples of Artificial Neural Networks performing Independent Component Analysis
Would someone point me to a reference/publication with a good example of an Artificial Neural Network that performs Independent Component Analysis?
Which types of architecture are suitable for this ...
0
votes
0answers
56 views
LIBSVM-based classifier assign very low score to positive validation files
Recently, I have been applying the LIBSVM to build a classifier based on a set of documents. The positive set has about 20000 files and negative set has about 50000 files. The built classifier is then ...
2
votes
1answer
214 views
Kmeans on “symmetric” data
A set is said to be fully-symmetric if for every x in it, negating one of its components results in y such that y is in the set as well.
A set is said to be semi-symmetric if for every x in it, ...
0
votes
0answers
80 views
Missing measure of variable importance for randomForest package in R [closed]
I have a problem with the importance measures given by the randomForest package in R.
I pass the parameter importance=TRUE to my ...
1
vote
0answers
40 views
Question on Precision and Recall
Is it possible to have both Precision and Recall to be equal to 1.
If such a case may exist, does it mean the system is over-fitting the dataset?
1
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0answers
19 views
question on presenting multiclass classification results [duplicate]
I'm trying to figure out how to present results (e.g. precision, recall, accuracy, ROC curve) for a class project.
I have a multi-class classification problem(specific classification algorithm not ...
