An algorithm is a a set of one or more computations that will produce a calculated result. All statistics methods are algorithms. Algorithms can be simple, such as calculating a percentage, or can be very complex and require a computer for fast and accurate results.

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Metrics for evaluating ranking algorithms

I'm interested in looking at several different metrics for ranking algorithms - there are a few listed on the Learning to Rank wikipedia page, including: • Mean average precision (MAP); • DCG and ...
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What fast algorithms exist for computing truncated SVD?

Possibly off topic here, but there exist several (one, two) related questions already. Poking around in the literature (or a google search for Truncated SVD Algorithms) turns up a lot of papers that ...
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GINI Algorithm flowchart [closed]

Salutations, I am learning the GINI algorithm (beginner) and I was wondering if there is a flowchart diagram and/or step by step algorithm of the GINI algorithm ?
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Randomly Generating Combinations From Variable Weights

The Question I have a list A of n unique objects. Each object Ai has a variable percentage Pi. I want to create an algorithm that generates a new list B of k objects (k < n/2 and in most cases ...
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29 views

How would I determine statistical significance for ad impressions?

I'm programatically adding keywords to bid on. Some keywords will trigger ads and impressions, and some impressions will trigger clicks. Clicks / impressions = CTR (click-through-rate). Clicks cost. ...
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2answers
29 views

Finding cluster number based on distance & max element count

Given two constraints: The maximum distance d an element can lie from a cluster centroid (or medoid) The maximum number of elements n in one cluster Is it possible to find the minimum number of ...
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27 views

How does one map a graph into a feature space?

Assuming there is an undirected weighted graph. How can one convey it's geometrical structure into a feature space? Are there any common practices?
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1answer
18 views

Algorithm to rank some items

Say I have some items with values 3.3 3.4 6.2 8.8 4.1 and I want to rank them as follow ...
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2answers
62 views

Weird Results in Newton Raphson

I am running a simple Newton-Raphson problem in R as given below. However I am getting very weird results. Can anyone tell me where I am going wrong? ...
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1answer
21 views

How do you differentiate a function in the em-algorithm?

I am conducting the EM algorithm. I understand the algorithm and my question is more related to the differentiation procedure within the algorithm more than the algorithm itself. Through using the ...
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2answers
42 views

Extreme outlier detection algorithm for erroneous latitudes/longitudes

I have a dataset with latitude/longitude of hotels of a "destination". A destination is a city neighbourhood, whole city, or small region, usually having between 3 and 50 hotels. About 1% of the ...
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19 views

Algorithms for Suggesting Users

There are often a large number of bug tickets that get generated for the projects at my company. I was thinking of an intelligent way for automatically suggesting users to assign to the tickets based ...
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1answer
32 views

Evening out a set of buckets

(I am not strong in statistics so please forgive me if I don't use the correct terms here) Let's say I have a book with many (1000+) sections, and each section varies significantly in the number of ...
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1answer
55 views

Meaning of the Boosting algorithm for Regression Trees

I have a problem with understanding the concept of the Boosting Algorithm. ...
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1answer
46 views

Algorithm to find common sequence

Assume that "1,2,3" are the ids of users, active means that person visited the stackoverflow in last one month (0=passive, 1=active), and there are positive and negative votes. ...
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An Algorithm for Maximal Correlation

Given a pair of random variables $(X,Y)$ over a product space $\mathcal{X}\times \mathcal{Y}$, the maximal correlation coefficient is defined as ...
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30 views

Comparing two algorithms by time series analysis

I have two algorithms. There is one vector of accuracy measurements for each algorithm. Each accuracy result in a vector corresponds to a moving average over a sliding time window and the vectors are ...
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35 views

Find meaningful next comparison for total ranking on the fly

I want to obtain a total ranking from pairwise binary comparisons. For this, I can use algorithms like Balanced Rank Estimation or Bradley-Terry Model. However, I wonder if you need fewer comparisons, ...
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12 views

How to fix co variance matrix going singular in Gaussian mixture model implementation?

I am implementing GMM in Matlab without using any machine learning library. I am able to initialize the parameters, perform expectation and maximization for one iteration; but when I put expectation ...
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1answer
64 views

data mining methods/algorithms for fraud case

I recently got into a topic regarding fraudulent transactions. I am relatively new to data mining and just looking for some input for my case here. I started with a cluster analysis / anomaly ...
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36 views

EM algorithm: With prior vs. not prior

I have a working EM algorithm without prior. I am asking for some advice on how to add prior on latent variables. Define: $t_i \in \{ +1, -1 \} $: variables of interest to be predicted $p_j \in ...
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2answers
61 views

Normalized gradients in Steepest descent algorithm

In general setting of steepest descent algorithm we have, \begin{equation} x_{n+1}=x_n-\alpha G_n, \end{equation} where $\alpha$ is the step size and $G_n$ is the gradient evaluated at the point ...
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28 views

Testing of the Grassberger-Procaccia algorithm

I've wrote the implementation of Grassberger-Procaccia algorithm in python. It is a method of reconstruction of properties of dynamical system by analysis of single realization. I would like to test ...
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2answers
66 views

Choosing an algorithm for classification

What determines what classification algorithm you should use for a certain classification problem? e.g. If there is >5 features or you only have 1000 training examples, or there is multiple class's or ...
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30 views

What machine learning algorithm should I choose to fill in blanks from context?

I have a project where I need to be able to fill in a missing word given a few words of context. In other words, suppose I have a sentence: I went ____ the store. I want to be able to deduce ...
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34 views

Recommendation system and baseline predictors

I'm participating in programming contest, where I have a data, and where the first number is a user, second number is a movie, and the third is a number in then-points rating. ...
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28 views

Algorithm to identify a correct input for only one number [closed]

Hello I'm hoping that you good folks here at CrossValidated can help me with this. I'm looking for an algorithm that takes an integer as an input and returns two types of values. One type of value ...
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What is the same or similar alogrithm in Weka for scikit-learn GradientBoostingRegressor?

I'm trying to move a GradientBoostingRegressor model to Weka. I have tried AdditiveRegression with different BaseLearners but the performance is very poor ( in terms of model quality and speed). I ...
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113 views

Computational complexity for linear discriminant analysis

The linear discriminant analysis algorithm is as follows: I want to conduct a computational complexity for it. For each step, the complexity is as follows: For each $c$, there are $N_cd$ ...
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1answer
92 views

Comparing classification algorithms using cross validation and caret's train

I am having issues understanding some concepts of algorithm comparison/parameter optimization/cross-validation in R Let's say I want to compare two classification algorithms, such as Random Forests ...
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12 views

Explanations about the parallel tempering

I am reading this paper on parallel tempering but there are a few things I do not really understand. If I'm not mistaken, parallel tempering is a MCMC method which is quite convenient to sample from ...
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33 views

Operations research problem to solve for out of stocks [closed]

I have a mathematical problem that I'm trying to solve and am wondering what kind of algorithm I should be looking at. I thought the revised simplex method would work but then I get stuck on knowing ...
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9 views

How to compute non-neighboring correlations using belief propagation?

Belief propagation is an algorithm to approximate the marginals of an arbitrary probability distribution. In principle, it allows you to compute the joint marginals at each factor node, which would ...
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233 views

Can humans cluster data sets manually? [closed]

Can human cluster data sets manually? For example, consider the Iris data set, depicted below: Instead of using clustering algorithms like connectivity-based clustering (hierarchical clustering), ...
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1answer
22 views

How to compute the $\chi^2$-table values?

How one can compute the values of $\chi^2$-tables? I saw two tables where was given for example that if degree of freedom is $1$ and $p=0.001$ then table value is in one table $10.827$ but in the ...
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1answer
104 views

Optimizing parameter estimates by minimizing chi^2 in iterative procedure

I need to minimize my Chi^2 (bottom-left in figure 1) by adjusting parameter-values in a MLE-procedure (or something alike). The chi^2 (red) is a goodness-of-fit measure. It expresses how well the ...
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53 views

Are there differences between Delta TF-IDF and TF-IDF?

Are there differences between both algorithm or not ? i mean if i implement for ex Delta TF-IDF in a project instead of ...
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89 views

Sentiment Analysis - How should I handle negatively biased word list length?

I'm implementing a simple sentiment analysis algorithm where the authors of the paper have a word list for positive and negative words and simply count the number of occurrences of each in the ...
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1answer
28 views

Best Clustering Algorithm for Protein data

I have 400 virus genomes. In each virus, there are 100 genes (these are rough estimates). The genes in these viruses are transferred between each other very frequently. So Gene5 of Virus1 could be ...
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18 views

Method or Algorithm to produce near-accurate probability selection

Are there any known algorithms or methods to accurately identify, using random occurrences, the most probable next occurrence(s) as a pre-determined length of number set, by providing an already ...
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50 views

Different behaviors for different Ridge implementations in R

I am having trouble reconciling the different behavior of different Ridge implementations in R. As the following code demonstrates it seems that MASS:lm.ridge ...
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1answer
59 views

Transform sample to achieve target mean, skewness, etc

I have a sample of data with N values from which I calculate basic moments such as mean, standard deviation and skewness. I will then change these moments to different values according to my own ...
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36 views

Minimize difference between adjacent elements in an array [closed]

How can I calculate the minimum possible difference between adjacent integer elements of an array. For example: We have the array: 11 14 14 9 16 Adjacent ...
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1answer
190 views

Is there an optimal way to find the best division of an interval of some positive integers?

I am struggling with a conceptual problem. I have positive integers from an interval [1800, 1850]. For every integer from that interval, let's say (without loss of generality) 1820, I have about 3000 ...
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1answer
174 views

One-Max fitness function (Java)

Whilst searching on Google about Genetic Algorithms, I came across OneMax Problem, my search showed that this is one of the very first problem that the Genetic Algorithm was applied to. However, I am ...
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1answer
127 views

What is a good model for revenue managment / price optimization problem

I am trying to create a dynamic pricing model to optimize revenue for a hypothetical business. Lets say I have an application that connects dog walkers to people who want to pay for their dog to get ...
2
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1answer
25 views

clustering verifying two basic invariance properties

disclaimer: I already asked something similar on stack overflow, but it seems to be a better place for that question here. I recently became interested in axiomatic definitions of clustering, cf. ...
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68 views

Decision tree with adaboost

Helllo! I'm currently learning the AdaBoost algorithm to use it with Decision Tree. I want to implement everything myself (that's the way I learn - implement everything from scratch and later use ...
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10 views

Training a function that maps n-dim to n-dim

As an example, say the input is an array of numbers representing an audio snippet and the output is a transformed/filtered version of it. What would be the proper term for that? Which are examples of ...
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28 views

Expected number of replacements during weighted reservoir sampling?

Consider the problem of taking a weighted sample of size $K$ from a stream of unknown but finite size $N$ in a single pass. Reservoir sampling solves this by assigning each item from the stream with ...