Statistical classification is the problem of identifying the sub-population to which new observations belong, where the identity of the sub-population is unknown, on the basis of a training set of data containing observations whose sub-population is known. Therefore these classifications will show a ...

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6 views

z-score normalisation

How does z-score normalisation actually work? (Within the context of classifier scores) I've seen various explanations but I'm unclear as to how it actually works. Most explanations seem to assume ...
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2 views

R Implementation of multi-class logistic regression classification algorithm optimization [migrated]

Although probably not needed to follow the question, the dataset can be downloaded here and once downloaded and placed in the R directory, loaded as: ...
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3 views

Score fusion vs Stacking

I was reading a post that used score fusion to compare two scores from two different classifiers (after normalisation). I read another that suggested feeding the results of these two classifiers into ...
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0answers
5 views

Why am I getting the same value for F1 and accuracy?

I trained and SVM classifier and I noticed that I'm getting equal F1 and accuracy values (using a cross-validation), which means that the number of True-Positives and True-Negatives is the same. The ...
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0answers
19 views

Does Gaussian discriminant analysis and linear discriminant analysis refer the same algorithm?

I'm pretty new to LDA and I came across other terminology called Gaussian discriminant analysis elsewhere. Since LDA assumes the normality or normal distribution of the data which is same as ...
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0answers
18 views

Classification of real values

I have values of attribute between 0 and 1 which i want to predict. The distribution of values is shown in fig. I want to predict this attribute. The problem is there are around 15 classes in this ...
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0answers
8 views

Statistically significant increase in Matthew's Correlation Coefficient

Suppose I have two classification algorithms A1 and A2, and a test set of size $n$. I evaluate A1 and A2 on this test set, and get corresponding Matthew's Correlation Coefficient scores ...
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16 views

Interpreting log-loss as percentage

I know that log-loss penalises models that are confident with the wrong predicted classes. Can this be translated to percentage accuracy? If not, then how do I report the error or compare it to other ...
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2answers
295 views

I did PCA of my dataset with two classes and here is the scatterplot; how can I tell if my dataset is learnable?

What should I look for in my PCA? I'm doing supervised learning with (unfortunately only) 2000 examples, evenly split into 1000 yes and 1000 no. Each vector is a 1000 dimensional boolean vector. I ...
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1answer
33 views

Machine Learning - How to use a classifier to find the most likely model

I have been learning about the use of machine learning algorithms and their application to particle physics. Now, I have some doubts concerning what to do with the results. Let me explain: imagine ...
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0answers
11 views

What is the best form (Gaussian, Multinomial) of Naive Bayes to use with (one-hot encoded) features?

I've been asked to use the Naive Bayes classifier to classify a couple of samples. My dataset had categorical features so I had to first encode them using a one-hot encoder but then I was at a loss ...
2
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1answer
16 views

Using the Naive Bayes classifier in R with continuous variables

I am trying to predict a categorical variable (type of job, there are three classes) using a dataset that mainly consists of continuous variables (like years of education, salary,etc), using the Naive ...
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1answer
19 views

How to represent no-detection in a confusion matrix

So let's say we have a multi-class classification problem and we want to represent the outcomes as confusion matrix. All the examples I'm finding on the web asume that all the elements are detected. I ...
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18 views

kNN bad performance for iris data set

I've implemented kNN algorithm in Python and now I'am testing it on iris data set. I have two questions. The performance seems to be bad: if I run the program 100 times and then calculate the ...
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0answers
18 views

Statistical measure for tf.Idf weight in document

I have 100 text document with different content size. I would like to label each document using the tf.idf weight. I have calculated tf.idf for the terms in each document. I plan to give the ...
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0answers
16 views

MCC or F-measure, which measure is the best to represent multi-class confusion matrix

I'm building a classifier of multi-class problem. In my context I have to classify vehicles into five categories: cars, vans, trucks, buses and motorcycles. I would like to use some measure to ...
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0answers
7 views

How to select weights in the F-Measure to be aligned with that used in cost-sensitive SVM training?

I am dealing with a classification problem in which Recall is more important than Precision, and the training dataset is an imbalanced one. The approach I am taking is to use oversampling to mitigate ...
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1answer
21 views

Is it possible to train a linear classifier to maximize f1-score?

The usual approach is to maximise f1-score is to train the classifier first and then optimize a threshold value on a validation set. The decoupling of weight learning and threshold searching sounds ...
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0answers
12 views

Extracting Lagrange Multipliers from SVM output in R [on hold]

I would like to extract the alpha lagrange multipliers from the SVM function in the e1071 R package, however I am not sure if svm$coef is producing these? Alphas are defined as in Equation 9.23, ...
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17 views

Why classification accuracy in validation set gets lower if validation cost also gets lower?

I'm training neural network for some simple classification task using tensorflow and have 2 output neurons, using softmax classification. My question is why accuracy on validation set gets lower when ...
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1answer
18 views

Use clustering to create labels of unlabeled data and then classify a test set (available or not in the clustering)?

Let's say that I use Dynamic Time Warping (DTW) along with K-Medoids to cluster unlabeled time-series into a number of clusters. In this way, several clustering solutions in $k_i,i=[1,...,m]$ clusters ...
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0answers
19 views

How to compare different models in H2O? [on hold]

I am new to H2O and I have just used in learning context. I am trying to figure out how to compare different models in order to chose the one with the best in a binary classification scenario. I have ...
1
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1answer
25 views

Why is SVM calculated in this way?

I have a question regarding SVM. I understand the Lagrange equation, $L(w,b,\alpha) = \frac{1}{2}w'w - \sum_i \alpha_i (y_i(w'x_i+b)-1)=$ $\frac{1}{2}w'w - \sum_i \alpha_i y_i(w'x_i+b)+ ...
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0answers
14 views

How to perform multiclass SVM classification using k-fold cross-validation and SMO with some kernel method in MATLAB?

I have data matrix X.csv file of size nxd, where n are the observations, and d variables. There are c_1,..., c_m classes. Let, Y be the matrix containing the class labels. There is no header row in ...
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0answers
14 views

Neural Network - Learning accuracy drops heavily after a couple of epochs

I designed a neural network to classify some images into 28 classes. Here are the parameters : Weight Decay : 0.005 Momentum : 0.01 Learning Rate : 0.001 and 0.005 Learning Decay : 1 Input : 100x100 ...
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0answers
6 views

Equal Error Rate (EER) and Receiver Operating Characteristic (ROC) curve

I have a one-vs-all classifier set. This set consists of, let's say, 3 classifiers (LibSVM SVMs) each trained on data for a class and all other class data. The current setup for a sample is that the ...
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0answers
6 views

Rebalancing doesn't give good results

We have a given a group of customers a price increase and as a result some have cancelled. We can identify exactly who they are because of the way they cancel. This means I can split them out from ...
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0answers
4 views

“Likelihood Ratio” for multiclass

If i have 2 classes, the likelihood ratio gives me a boundary like the image below. What if i have 3 or more classes ? What test can I use to classify an input data ? What if it is a mixture of ...
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0answers
23 views

can I use the cluster membership from cluster analysis for future prediction (classification)

We had a survey of >1500 patients, and we did cluster analysis, and grouped them into 3 clusters. We want to develop a algorithm to predict cluster membership of future patients. But the question is: ...
1
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1answer
23 views

Bayes optimal classifier vs Likelihood Ratio

I am getting slightly confused by all the probabilistic classifiers. The bayes optimal classifier is given as $ max (p(x|C)p(C)) $ and if all classes have equal prior then it reduces to $ max ...
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0answers
9 views

“Multiclass Likelihood Ratio” - Help please?

I am reading up on this paper which is basically about classifying pixels as a target or background using the likelihood ratio test. But LRT is only for 2 classes. What if i have more than 2 classes ? ...
1
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0answers
22 views

What exactly is the mathematical definition of a classifier / classification algorithm?

I just started an intro machine learning course, and to get things better organized in my head, I was trying to come up with exactly what is needed to completely specify a classification algorithm. I ...
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1answer
22 views

xgboost parameters - how can we use max.depth parameter with binary:logistic objective

I'm new to xgboost package and here is the doc on the parameters of this library for your reference. My question is, logistic regression doesn't do binary splitting and build a tree unlike decision ...
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2answers
36 views

Is it possible to make the non-separable data more separable by any methods of feature selection, extraction or transformation?

Could these data (in the figure below) be separated by any means of feature extraction, transformation, or it's just a waste of time to make the three classes separable if they "in fact" weren't ...
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1answer
23 views

How to make this data in the following figure separable for the classification into three classes?

The figure below shows the PCA projections of inputs which are 14 meteorological features, (i.e. wind, temperature, humidity, pressure, and so on.) I would like to use any technique to make it more ...
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18 views

Combining probabilities [duplicate]

I apologize in advance - I'm asking as a relative novice and may be using incorrect terminology, or may be missing a similar question already posed on this site. Let's assume I have a classification ...
1
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1answer
27 views

What is the origin of the rule of thumb for the number of samples needed machine learning?

I've heard that as a rule of thumb, the number of samples needed for a machine learning algorithm to get accurate results is ten times the number of degrees of freedom. For example, classifying an 8x8 ...
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0answers
7 views

Adaptive classification model

I have come accross a tipical situation where right now i am aware of very few classes and more classes are likely to come with time. I have training data for theae known classes. Once new classes ...
0
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0answers
18 views

Best practice of ratio of labels in the dataset for a classification problem [closed]

In a classification problem with two labels, label_1 and label_2, is there a formula or at least a rule of thumb / best ...
1
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2answers
37 views

Classification, create a grey zone

I want to create a "grey zone" for a binary classifier. Grey zone means, in this zone classifier should give the result "I don't know". I denote classes with + and -. I have good tpr , but not so ...
0
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0answers
7 views

XGBoost on Python: Plot performance

following the instructions from https://xgboost.readthedocs.io/en/latest/python/python_intro.html after building my model, i tried on Jupyter (using Mac OS X, Chrome browser) ...
2
votes
1answer
29 views

SVM cost function: old and new definitions

I am trying to reconcile different definitions of the soft-margin SVM cost / loss function in primal form. There is a "max()" operator that I do not understand. I learned about SVM many years ago ...
0
votes
1answer
18 views

XGBoost on Python

Hi could someone explain what the num_round parameter is for ? it is not well explained in the official doc http://xgboost.readthedocs.io/en/latest/python/python_intro.html on that page, a (typical ...
0
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16 views

Suitable non-deep classification algorithm for binary images

I've to classify images of hand shapes like this: I've tried this methodes actually: SVM with contour vector of the hands shape as features PCA on images pixels + SVM Have you other ideas to ...
0
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0answers
14 views

simple temporal classification with LSTM

I'm working on a sequence labeling for specific type of data using LSTM network. However at the moment i'm trying the algorithm with some toy data. I've written the matlab code to implement the ...
0
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1answer
32 views

Can cluster analysis of preclassified items gives idea about the classification performance?

Suppose in a classification we have a dataset with many features and their class, we want to select some features using which we can construct a classifier. We perform the cluster evaluation for the ...
0
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1answer
75 views

Cross-validation of multiple subjects with multiple instances

I have a training set of 50 subjects with about 550-600 measurements each. One measurement consists of 24 features and one class label (1 or 0). So my data looks like this (simplified): ...
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13 views

Can Lloyd's algorithm be implemented in Knn?

I have seen papers that uses Lloyd's algorithm that could optimize K-Means, but i was wondering if the algorithm can be used to K nearest neighbor.
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2answers
16 views

Non-linear transformation to increase separability between clusters

I want to do a classification on PC scores. I have a 400 dimensional matrix, e.g. 2000*400 (2000 number of samples and 400 dimensions). I fist apply PCA on it and take it to 3D, i.e. 2000*3. There are ...
3
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1answer
56 views

Indoor location using WiFi Signals and Machine Learning

I am trying to determine in which zone of a building a person is located based solely on the strength of the WiFi signals her cellphone gets. Currently, we are making measures with an Android App, for ...