Tagged Questions

Questions on the use of mathematical techniques to extract properties from given data. Consider if your question might be more suited for Cross Validated (stats.SE) instead.

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Cohen's Kappa and MovieLens

I'm tryings to analyse the MoveLens 20m data set and I'm interested at looking at user rating agreement levels. Someone has suggested I look at Cohen's Kappa as this kind of inter-rater agreement is ...
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What would be a good algorithm to determine the busiest servers by cpu usage

I have a huge data set that contains time series data for some servers' cpu usage per application. I need to find the busiest servers to for the application and print it. I need to find a method or ...
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Penalty function of multi-peak fit?

The question I have is about the answer from here by @Silvia: http://mathematica.stackexchange.com/questions/26336/how-to-perform-a-multi-peak-fitting I can only understand some of the code but the ...
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What is the order of this algorithm?

I was messing around with a method of manipulating strings in Java when I came across this algorithm. For a string of length n: $$\{1, 2, ... ,n - 1, n\}$$ rearrange it such that the first character ...
41 views

Create a modal line or benchmark

I have some data the following, X is cycle in percentage, and Y is the quantity: ...
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How to infer information from a cumulative frequency graph, and what it means practically

So I'm given a table of data, regarding "An estimator working for a large construction company, is preparing a tender and trying to establish a rate for reinforcing bars in a concrete floor. Data ...
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Is the sum of all cross-correlation samples representative of target existence likelihood?

Answers to this question take the peak in the cross correlation as the measure to the likelihood of the trigger signal exist in the received signal - this is pretty much text book. My question is ...
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Find errored member in a dataset

Assuming a simple data-set looking like this dataset As you can see there is 10 lines, each one representing an entity. For each entity, there is an amount of downloaded and uploaded data which are ...
29 views

How to profile people using clustering

I have a data of customers and i want to split them to segment (profiling). The columns of the data are Amount-Spending, Amount-Bonus, Age, Churn-or-Not. So i clustered my data with k-means. to 3 ...
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What is the algorithm for training and testing a logistic regression model using Newton's method and l2 regularization?

I have a spam dataset with 57 features and 3065 data points. I also have test data with around 1500 data points. The classes are spam/non-spam. I have to fit a logistic regression model on MatLab ...
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How to obtain the best fit?

I have a complex function say $f(x,a,b,c)$ where $x$ is variable and $a,b,c$ are the parameters. Parameters $a,b$ are linked as $d = (1/a^2) - (i*pi/b)$. The limits of x is very small say -0.02 to 0....
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Choosing between several methods to replace bad or missing data.

We are doing some quality control on data coming in from stations all over the world. Part of the quality control involves testing the data on several different things like plausibility, etc. If a ...
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time series regression data set

I am trying to find a data set to which I can apply a regression time series model. So I need a data set where the regressors(predictors) of the model are also time series themselves. where can I ...
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Formula that devides date(given in millisecounds)

Just to clarify at the offset, i am a javascript developer and this is a Math question , so my question is as follows: suppose i create to dates in javascript like so: var d1 = new Date(2005,12,4);...
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What is the probability of having the same (binary) datasets?

Suppose we have $m$ binary data points as an outcome of a specific experiment, so the outcomes of those points are fixed. We save our data in a file of $m$ points having value $0$ or $1$. (for example ...
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Finding the weighted mean with varying errors

Simply enough, I've a set of numbers with varying errors: 2.02 +- 0.10 , 2.26 +-0.30 , 3.24 +- 0.30 , 3.33 +- 0.30 , 3.92 +- 0.30 , 4.02 +- 0.10 I'm certain there's a simple formula to compute the ...
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How to find a data value using only standard deviation?

I have a homework problem with the following data values: x, 17, 24, 13, 21. I need to find x, but I do not have the mean. I only have the standard deviation, which is square root of 14, or 3.745. How ...
376 views

Finding the orientation of a noisy ellipse

This question comes from a neuroscience study which generates $12$ vectors. The vectors are evenly spaced, $30 n$ degrees for $n=0,\dots, 11$, each with their tail centered on the origin. I am ...
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Analysis of rank/likert scale data

If age groups/gender represents independent variable(s) and responses have been collected for 5-6 items in the form of ranking (most preferred - rank 1 to least preferred rank - 5). Which test is an ...
32 views

Markov-Chain Monte-Carlo: Are transformations on the inputs valid?

The problem: I am trying to solve a high dimensional (up to ~50) class of data fitting & modelling problems. The user specifies the problem, so I would like to make the configuration as easy as ...
107 views

weighing avg by columns vs rows outputs different results

First of all, I just know the basics of math, so please be patient. I have an overall score for a company with the product1 and product2. However when I do the overall for each criteria like ...
37 views

How do I find if a series of integers is (somehow) regular

[DISCLAMIER]: please be patient and low profile: no math background here :) I have a database of transactions, i.e. a list of purchases made by different customers. What I have to figure out is ...
50 views

Curvature of a 3D trajectory for which I know data points

In order to simulate an airplane model, I need to change its orientation knowing the curvature of its trajectory. The simulator gives me the plane position, so in order to perform my orientation ...
72 views

Interpolation at “extreme values.”

I am working with a meteorologist on a project. We are pulling data from METAR Observation stations on several variables (such as temperature, dew point, wind speed, etc.) throughout time. ...
42 views

Non-Whole Median Numbers in Real Data [duplicate]

According to this CDC report, the median number of reported sexual partners for females aged 15-44 is 3.2, and for males 5.1. Tables on pages 19 and 20 report these statistics for a variety of ...
86 views

Outlier detection with robust multiple regression model

I have a set of features (eg, location, income, budget, education) that I use to predict a continuous variable (say, amount spent per day on the internet). I am interested in detecting outliers. I ...
42 views

Matlab, Extracting Particular Values from an Excel File

If I have a table of values in Matlab ( here I have a 40k rows, and about a dozen columns), how can I read only particular values from each row? My goal is to extract some of the values from each row, ...
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intersection of 2 paths

Could somebody please advise me on the best approach to take to find the intersection points of 2 paths. Each path is a data set of distance against time (I want to avoid curve fitting) and each path ...
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Averaging Models in Excel

I am working in Excel and have two sets of data points that come up with a percentage for the likelihood of a recession. I am wondering what the best strategy would be to combine these data points? ...
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Calculate trend and represent in text?

First off, I'm terrible at math. I'm writing a script that monitors transactions from clients daily over a 7 day period. Given a set of numbers like below, I would like to calculate a trend and ...