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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17 views

Calculate pdf and cdf of exponential random variable

I am not looking for an answer as this is for a homework exercise i just want to be pointed in the right direction so i can learn how to do it. The question is: Let X ∼ Exp(λ). Calculate the cdf and ...
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6 views

Testing Relative Preference Fit (multi-variable)

I'm playing around with a data set that I have built which is meant to represent the subjective preferences of a person related to a particular product. I want to compare, then, the properties of a ...
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0answers
12 views

Hypothesis Testing with given Pearson correlation.

There are two independent sets of samples , female and male. The problem is to calculate the 95 % C.I. of the mean of total( male+ female, two samples) population. -> Female : n=100, mean= 169.1, sd ...
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20 views

Quantify difference between regularity and irregularity

I am solving an equation numerically on a 1D-domain using the finite-element method. I am solving it using two different domains, one regular and one irregular. Naturally, the solution varies slightly ...
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3answers
37 views

pdf of sum of two dependent random variables

What is the pdf of sum of two dependent random variables given we know their joint pdf and individual pdfs. I have seen already some posts but none of them answered when they are dependent. Every one ...
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1answer
19 views

Polynomial Fitting of Circular Data Object

This is a very odd question. I have a one dimensional data set that is graphed on a histogram. I am trying to curve fit this data set (using the class midpoints as the x values, and the frequencies as ...
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8 views

Is EM-algorithm only for missing data?

Currently studying EM algorithm and have been through a few articles, they all say it is for missing data. I believe there is some implication in the term "missing data". I wonder if EM is designed ...
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2answers
25 views

Plain English interpretation needed for the sentence to understand EM-algorithm?

I am trying to read an EM-algorithm article on the web, however, as soon as I started I have face a sentence interpretation problem with this like "... in the presence of missing or hidden data" in ...
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0answers
41 views

What is the relationship or difference between MLE and EM algorithm?

I am trying to study EM algorithm and Maximum Likelihood Estimation. Somehow, they both sound the same to me but can't really say the difference. Maybe I don't really understand any of them. I have ...
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1answer
19 views

Analysing data to find the principal parameter

I have a data set $N\times M$, which contains information about motorcycles: $N$ motorcycles have been sold during some time and for each bike there is $M$ parameters regarding the sale such as price, ...
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11 views

Statistical significance of deviation from a complex-valued model

I have complex-valued data. At each one of about 100 linearly spaced $x$ values, I have a corresponding measurement of a complex quantity with well-defined Gaussian uncertainties on both the real and ...
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0answers
33 views

Distribution of the test statistic?

Let $\mathbf{x}_i \sim \mathcal{N}(\boldsymbol\mu, \boldsymbol\Sigma)$. I am trying to find a distribution of the following test statistic $ T(\mathbf{x}) = \frac{\bar{\mathbf{x}}^H ...
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6 views

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 ...
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0answers
17 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 ...
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0answers
15 views

Finding trends in data with multiple variables, analysis software?

I have a series of many test results (hundreds). They are vibration test results of electronic equipment that has been built the same standard way (same materials, adhesives, structural shape and ...
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2answers
91 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 ...
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0answers
15 views

How can I determine an efficiency equation for this problem?

At work, I have been tasked with taking all of the relevant information regarding our production lines in order to determine the efficiency of all of our assembly lines. Below is some of the criteria ...
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1answer
35 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 ...
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1answer
24 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 ...
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0answers
25 views

Can I solve these simultaneous questions, and if so, how?

I have a set of paired experimental observations (Fo, Bo), e.g. 1.55, 8.52 4.56, 36.36 21.03, 64.98 (> 6 data pairs in total) which I believe can be modelled as being generated by Fo = Ft + a.Bt ...
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0answers
35 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. ...
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0answers
7 views

Statistical Significance of Modified Data

I would like to know the statistical significance of achieving 1 or 7 100% of the time in a dataset of nine possible values. The nine possible values are the digital roots of a string. In a random ...
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1answer
24 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 ...
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0answers
27 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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0answers
22 views

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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0answers
19 views

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? ...
2
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1answer
41 views

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 ...
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1answer
21 views

How to convert table into a distance function?

Been stumped on this past paper question for a while, it's in the context of clustering and the next part is using single linkage bottom-up hierarchical clustering to form a dendrogram using your ...
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1answer
30 views

How can I maximize the sum of y values across a given number of graphs?

I have any number of graphs. Each graph is a plot of points, not necessarily an equation. I need to pick a point on each graph in way that the following is true: The sum of the y values of each ...
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1answer
21 views

Slightly convoluted problem I need help solving involving the percent change formula.

I was hoping someone knows the solution or has an alternative form of approach. tried this out over on /r/askmath with little response. Ok I will attempt to be as clear and as simple as possible. I ...
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1answer
28 views

Probability of a Collision in Selection of Permutations

Suppose I have a set of characters, say $\{a-z,A-Z,0-9\}$ $(n=62)$. Then I select a random permutation each containing $10$, e.g. $k=10$, characters. What would be the probability of a collision ...
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0answers
64 views

Deal with circular standard deviation

I have a sensor that gives me a direction of the target in degrees with a certain standard deviation and I use a circular probability density function (PDF) to represent probable locations for the ...
2
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2answers
42 views

Inversion of the Burrows Wheelers Transform

The "Burrows-Wheeler Transform" in signal processing is a transformation which is used in for instance data compression and pattern recognition. It can be described in mathematical terms as: Start ...
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1answer
22 views

Clustering elements according to covariance matrix

I'm doing a little bit of topic modelling (which is not really my area) with twitter tweets. The situation is the following: I have a (sort of) covariance matrix where the entrie $C_{ij}$ corresponds ...
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0answers
18 views

Methods for Extrapolating Data Close To Observations

I am aware of many different ways to go about interpolating between the values of known data points. However, whenever I come upon (I work in Quantitative Finance) the need to extrapolate data I find ...
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0answers
13 views

Random data generation from a bivariate distribution

Let $X$ and $Y$ be non negative random variables with joint distribution \begin{equation} F(x,y)=1-e^{-x}-e^{-y}+e^{-x-y-\delta xy}; ~~~x\geq 0,~~y\geq 0. \end{equation} How to generate a bivariate ...
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5 views

How do I find the weighted mean of maxima for a granulized data set?

I have a dataset for which I had to apply Wang-Mendel algorithm. The aim is to find the y value when x=14. I granulized and approximated the data and found the rules in the Mamdani format. Now I have ...
2
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3answers
67 views

Parameters estimation for gaussian function with offset

I've read the paper Least square fitting of a Gaussian function to a histogram by Leo Zhou on how to perform a Least Square Fitting of a gaussian function to a histogram. The Gaussian function used ...
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2answers
626 views

Way to compare three numbers with an algorithm.

Say I have values 10, 3, 6 What would be a way of finding a subjective difference between them. Or in other words, how close they are to each-other. So if i had 3, 2.5, 2.8; they would be close ...
2
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1answer
25 views

make the mean of 2 data sets the same

I am in the process of computing my student's final scores and for some reason I couldn't figure this step out: If I have 2 data sets of scores in the range [0,40] but one data set has a different ...
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0answers
26 views

Representing a Concept

From Formal Concept Analysis: If I have a set of objects: G={Shark, Penguin, Bat} and a set of attributes: M={Breathe Underwater, Can Fly, has Vertebrae} and I make a chart to represent my ...
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1answer
57 views

Using Excel to calculate relative difference between three numbers

Background I am trying to produce a table of values for the positioning of the hands of a clock at any time, limited by one second intervals, to demonstrate the feasibility of an ultra precise, ...
0
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1answer
39 views

Function to convert all -ve numbers into their +ve counterparts without affecting present +ve values (-12 to 12)

I am essentially after a function that will convert negative values in my Excel spreadsheet into their positive equivalents without affecting the present positive values. A sample of my data would ...
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0answers
37 views

Mathematical equivalent to curve fit between polynomials

I am adapting a calculation done in an Excel workbook to code. Right now, we are predicting a variable based on three other variables, say $x,y,z$. We are creating six functions of $x$ and $y$ at ...
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1answer
38 views

Interpreting Entropy

All you data scientists will probably know the entropy equation: $$H(p)=-\sum_{i=1}^{n}{{p}_{i}}\cdot\log_{2}{{p}_{i}}$$ And, using this, I was messing around with some compression, and calculated ...
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1answer
12 views

What measurement should be used to determine per unit capacity of a given volume ish question

I am reselling data packages and would like to add a sense of scale to the packages. Without disputing actual numbers, an email message is between (3-20)Kbytes, a photo 270kb, a web page ...
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0answers
10 views

Is it always possible to find a logistic regression model that yields zero training error on any dataset?

I am leaning towards no. A logit regression model is just one function, and there is no way its coefficients can accurately predict an entire dataset, outliers and all. Is this the correct intuition?
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2answers
65 views

How to verify how good my data is?

I'm in an undergrad physics lab right now and I have taken some data. The theoretical curve should be proportional to $\cos^2(\theta)$. How can I quantify how close my data values are to this ...
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0answers
14 views

When to use the various mean functions (arithmetic, geometric, quadratic) appropriately?

In data analysis, when are the use of these different means appropriate? For example, I'm using data to infer the peak of waveforms at different points around a semicircle. If my data has intensity ...
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0answers
9 views

Montonicity and Nonlinearity in data

I wish to find out why the following function $y_i=\sum_{l=1}^N\frac{ \theta_l}{1+ \exp-(\sum _j^M \theta_j x_ij +b_j ) }, i=1,\dots, P$ shows a linear, monotonic relationship instead of a ...