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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Measuring entropy of a 2d matrix

In this answer to the question Measuring entropy/ information/ patterns of a 2d binary matrix, the base-2 entropy of the 2-d matrices obtained from a series of moving window sum filters is measured: ...
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LexRank damping factor

I am looking into using LexRank to do some text summarization. I am looking at the original paper. One thing that puzzles me is whether a damping factor is used or not. The formulae are all using it, ...
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Learning to write your own estimation algorithms - where to start?

I am trained as an epidemiologist. Early in my career, statistical models were a black box, and when in doubt I was advised to go see a statistician. This never sat well with me, so I became ...
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clustering algorithm for real time event [duplicate]

I have a question? which clustering algorithms is good to detect any kind of significant changes, named as “Event” in real time event ,specially for spatial temporal analysis of Flicker, Twitter ...
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Entropy estimation for a symbol sequence

I am looking for an R-implementation of the Lempel-Ziv data compression algorithm, to estimate the source entropy of a time-series consisting of a sequence of symbols. Rather than simply measuring ...
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1answer
46 views

Pegasos prediction time

I have been implementing the (kernelized) Pegasos algorithm, but am running into problems in terms of scalability. I will use notations as in the original manuscript. Here's a typical time ...
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29 views

What are the proper ways how to add noise to a dataset? (algorithm data sensitivity analysis)

Consider: dataset defined as n datapoints x_i in m-dimensional space. And there is a label ...
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16 views

Possibilities of accelerating EM algortihm

I'm trying to use the EM to estimate some parameters. I've programmed and it delivers. The problem however is that for each run of my programme, it can take either 5 seconds, 1min, 3min or more to ...
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27 views

What would you use as your default model for comparison?

I have a question. Say you are given with like 1500 instances as your dataset, in which instance will be categorized into 1 of the 3 classes. You're supposed to come up with the best model from the ...
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Estimating the number of streets in $CITY?

I'm not sure if this is the right place to ask these kinds of questions. I want to estimate the number of streets there are in a certain city. Any advice? How would you begin? (To be precise, I want ...
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22 views

Clustering algorithm for my situation?

Here is my situation. I have a corpus of over 500,000 news. Now I need to cluster the news based on closeness in time and cosine similarity, using vector-space model and TF-IDF weights. I want to ...
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24 views

Random sorting of an array of weighted scores

I'm trying to construct an algorithm that randomly sorts an array according to a weighted score for each item. In the most straightforward version of the algorithm, the output array can be ...
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23 views

Regression clustering

I am looking for references about classical methods in regression clustering. My problem is the following: I have a cloud of points that are assumed to have been generated by inverse functions with ...
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How to extract “average polyline” from a set of polylines [duplicate]

EDIT: As pointed, there is already a similar question "buried" inside a larger-scope one. I'll reproduce the relevant part here: If I have multiple recordings of the same routes are there any ...
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41 views

Single-pass algorithm for kurtosis

Here is a simple test I've run on MATLAB to check the validity of a single pass (online) algorithm for computing $3$rd moment and $4$th moment. ...
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2answers
103 views

Maximize sum of f(x), where f(x) is unknown, but we learn as each x is chosen

Let's suppose that I have a function like below, but I don't know what it is. However, as I choose x, I know what corresponding ...
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Find bound pairs/subsets

I have 6000 sets of ~350 items each, all from the pool of ~13800 items total. Items in each set do not repeat. I want to find rules like "if 1398 is present, 1035 will most likely be present too". ...
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Computing Standard Errors in EM algorithm

I'm applying the EM to a hidden markov chain (the $\mathbf{Z}=\{Z_1,...,Z_n\}$ variable), with observations(the $\mathbf{Y}=\{Y_0,...,Y_n\}$ variable) dependent not only on the hidden markov chain, ...
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23 views

References for Bayesian change point magnitude estimation

This paper by Adams and MacKay provides a computationally efficient algorithm for the online estimation of change points in a data sequence. I am looking for similar material that estimates not only ...
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46 views

Reconstruct a “blocky” picture?

Consider a finite set $A$. Let the sample space be $A\times A$. We have an unknown probability distribution $f$ on this sample space. Now this probability distribution has a "blocky" property, which I ...
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Number of occurrences gives higher weights

I have this algorithm that I'm implementing that I need to change to give it a better accuracy. To give you an idea of the problem, I have a a bunch of lists that contain items and all items in these ...
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1answer
57 views

Name of algorithm (or paper) that scikit-learn cluster.estimate_bandwidth() function implements for meanshift bandwidth selection

Can someone tell me the name of the algorithm (or paper) that sklearn.cluster.estimate_bandwidth implements and is used by the meanshift algorithm implemented in Scikit-Learn to automatically select ...
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1answer
46 views

Using KNN for 2 Dimentional data

I am dealing with sentiment results of web articles. Sentiment is represented with two int values, +ve and -ve. For given article "xyz" I am getting different sentiments while testing at different ...
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What are the algorithms to detect bots clicking on a shortened URL?

I own a url shortening service. I want to deliver only legitimate statistics to my clients. There are possible scenarios that a particular user writes a script to automatically open the shortened URL, ...
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1answer
31 views

exponential approximation at adaboost

I am reading about AdaBoost algorithm, I cannot understand (7). How can it be like this? If you want full document, you can get it at http://cseweb.ucsd.edu/classes/fa01/cse291/AdaBoost.pdf ...
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1answer
62 views

Cholesky update for removing row

What is most efficient way to updating cholesky factorization of for removing a column from the matrix? T = Chol(X' *X) If I remove a column from X, how to ...
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1answer
78 views

LogLikelihood Parameter Estimation for Linear Gaussian Kalman Filter

I have written some code that can do Kalman filtering (using a number of different Kalman-type filters [Information Filter et al.]) for Linear Gaussian State Space Analysis for an n-dimensional state ...
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27 views

How to rank users?

I have a list of movies ranked out of 5 based on their income. I have users ranking the same movies. Not all users rank all movies. How can I find out which users have the best correlation between ...
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77 views

Difference between Random Forest and MART

I just wonder what is the difference between Random Forests and MART (Multiple additive regression trees)? I have read a few articles, e.g.: [1] L. Breiman. Random Forests. Machine Learning 45 ...
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41 views

Expectation Maximization Clarification

I found very helpful tutorial regarding EM algorithm. The example and the picture from the tutorial is simply brilliant. Related question about calculating probabilities how does expectation ...
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41 views

How to calculate ratings/rankings from Paired comparison / Pairwise comparison of large data-sets?

As part of my graduate thesis (area: psychology) I have gathered preference data. The data includes approximately 50000 heads-up comparison between elementX and elementX. I have a total of 15 ...
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42 views

Fitting a model to correlated data

Trying to fit a model (bloch equations from MRI) to experimental data (12 parameters, 12 equation). Monte Carlo Multistart ('lsqcurvefit' in MATLAB) gives expected values for all parameters except for ...
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37 views

Future value prediction for unsampled data

I am trying to study various factors that result in a single outcome. For example, if we look around factors that results in the stimuli reaction of a person, let's say the heart beat, the blood ...
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1answer
53 views

Algorithm to take samples from binomial data

I am faced with the following problem : I have binomial data, ie. data of the form trials/successes, with a list of features. What I need is to sample without replacement from that data, ie. take a ...
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41 views

Why do matching algorithms use point estimates rather than intervals?

I'm developing a matching algorithm, and I am wondering why websites choose using point estimates, e.g. "You match 60% with person X". Given that there will be most likely be missing data, rather ...
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66 views

Does this data type require this manual standardisation, or can this be circumvented using a random forest classifier?

I have some data that represents students exam scores, this data is used to predict what rank the student will be in 'todays' exam. Some of the data I use in order to predict this is the previous exam ...
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1answer
81 views

Linear Combination of multivariate t distribution

I am looking for a resource where i can find derivation of the linear combination of multivariate t distribution. Does anyone here know any good site or place (s)he can point me to? I am trying to see ...
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1answer
65 views

Assumption to make on data so that we can have an approximation of the final number of representatives

Let $t$ be a distance threshold (user-defined parameter). $X$ is a dataset containing some $p$-dimensional data-points. $L$ is a list of representative-data collected from $X$. Given the following ...
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1answer
63 views

Re-ranking a list

I have a ranked list say A,B,C,D,E,F,G and a subset of this list ranked with another strategy lets say D,B,C,F. And my assumption is that the strategy used for ranking the sublist is better because ...
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3answers
139 views

How to find the number of clusters in 1d data and the mean of each

We have a list of prices and need to find both the number of clusters (or intervals) and the mean price of each cluster (or interval). The only constraint is that we want cluster means to be at least ...
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Why PCA of data by means of SVD of the data?

This question is about an efficient way to compute principal components. Many texts on linear PCA advocate using singular-value decomposition of the casewise data. That is, if we have data $\bf X$ ...
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1answer
35 views

Average of arrival times excluding outliers

I'm working with a dataset of arrival times as below: ...
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97 views

Outlier detection in very small sets

I need to get as accurate as possible a value for the brightness of a mainly stable light source given twelve sample luminosity values. The sensor is imperfect, and the light can occasionally ...
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1answer
145 views

Apriori candidate pruning

Dataset of frequent 3-itemsets before running the algorithm: ...
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1answer
152 views

Canonical Correlation analysis without raw data

I want to run a Canonical Correlation (in R) but I don't have the original (raw) data. I have only the correlation matrix of all the variables. I have seen some ...
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1answer
48 views

Algorithms/methods for detecting regime changes in data rates

I'm looking at multiple live data streams which I process on a daily basis and would like to monitor in real time. The way I did it at first was to introduce a somewhat arbitrary upper bound for ...
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38 views

Need help finding a suitable online learning algorithm

I would like to build a system that attempts to predict which items a user would like, giving each item a "score". An item is really a collection of textual tags, and each item is presented to the ...
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1answer
140 views

Convergence of value iteration

Why is the termination condition of the value-iteration algorithm ( example http://aima-java.googlecode.com/svn/trunk/aima-core/src/main/java/aima/core/probability/mdp/search/ValueIteration.java ) as ...
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27 views

Algorithm implementation help

I was reading a paper by Cui et al., "Discover Breaking Events with Popular Hashtags in Twitter". I was trying to implement their hashtag instability algorithm, I do not understand the actual ...
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Reliability standard via relative standard error for computer science or randomized algorithms

I am performing experiments on randomized algorithms, and want to do it scientifically sound. What relative standard error of mean (RSEM) is acceptable? I know that often RSEM<30% or RSEM<25% ...