Refers to the interface of statistics and computing; the use of algorithms and software for statistical purposes.

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18 views

How to find extreme values in a dataset in R? [on hold]

I have a dataset containing cities and their corresponding CO2 emissions. I want to find which cities have emissions too high or too low according to mean. Which functions in R can I use to find these ...
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2answers
19 views

How to analyse the accuracy and standard deviation of a neural network in matlab toolbox? [on hold]

I am new in Matlab and neural network, and I am doing a prediction with some data that I found on the internet to learn more about it. Here is my function to create a neural network: ...
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9 views

What is the best way to analyse data comparing one by one and stipulate the accuracy?

Follow the example: The first line is the data I got. The second line is the target data. | 154.0 | 784.4 | 854.1 | 789.3 | | 153.5 | 789.7 | 892.3 | 903.2 | I ...
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1answer
34 views

Is Representer theorem valid with constraints on coefficients?

By the representer theorem, we have that in a Reproducing Kernel Hilbert Space the function being learnt in a regularizer + loss function problem under some conditions, can be represented as $\sum_i ...
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1answer
29 views

What is the standard way to distinguish the errors associated with sampling and measurement in statistics?

This is probably a very basic, yet not easy, question in applied science. I was just wondering, what are usually the standard ways to deal with it? Any pointers to further references are greatly ...
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35 views

Sample size when using GPS-trackers to analyze movement of reindeers

If one were to try and analyze the movement of ~2 500 reindeers before and after a (man-made) change in landscape have occured. Specifically how spread out the herd is, both as a whole and if there ...
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12 views

Realistic simulation of instrumental data

I want to simulate data collected by an instrument realistically. The problem is that if I use simple Gaussian deviates then an analysis program can guess the truth simply by computing the mean of a ...
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1answer
40 views

What type of Anova to use and how (in R)?

I tried to find differences between delta G values in amino acids between 9 species. Here is a link to the table that I read in. (The header lists the species): ...
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14 views

How to determine correlation between sets of integers

How would I determine a correlation between sets of integers such as the following: set A: 1, 2, 3, 4 set B: 2, 3, 4 set C: 4, 5 set D: 2, 5 I want to have a ...
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9 views

Calculate basic statistics for stream of binary data [closed]

I was reading this thread and started to think if there are any statistical tool to analyze binary data. I am mostly interested in the R project since it has good data-analysis tools for decimals ...
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4 views

Find the expected frequency of some state in a state sequence of length N given a transition matrix M

I can represent stochastically-articulated sequences of states using a transition matrix M where a given entry in cell (i,j) corresponds to the probability of state j given that the current (or, most ...
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32 views

In R, line slope changes when only x values as shifted

I'm new to R, and trying out few examples in it. I'm trying to find the slope of a plotted graph, using lm function. My code: ...
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1answer
83 views

KPSS test outputs and DF test interpretation

I am running a Kwiatkowski–Phillips–Schmidt–Shin test (KPSS test) in R (urca::ur.kpss). However, I am quite unsure if it is performed correctly, because the ...
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1answer
37 views

Estimate lag for granger causality test

I am using the granger causality test to check my variables for causality.+ Here is my code: ...
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1answer
34 views

How to interprete lasso from lars correctly?

I tried the lars package with R and got the following result. ...
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2answers
66 views

Reference request for beginner in SAS

I am interested to start learning to use SAS, I have used R for some time but for me SAS is a novelty. I do not seek any material in particular, since I'm now beginning to take the first steps with ...
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2answers
34 views

Test for statistical significance in performance variability

I'm analysing data collected from a call centre activity in which agents are calling prospective leads. For each call made, if the lead coverts the call is a success and if the lead does not convert ...
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1answer
71 views

Anomaly detection in time series data

Hi I have a large data set of objects, each containing a list of the same attributes. The data is arranged in a time series so that the value for an attribute for an object is indexed by its time. I ...
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1answer
45 views

Explanation of the different variable types in statistics?

One thing that has always tripped me up when trying to learn new methods in statistics is understanding what type of features/variables can this method be applied to. The variable types that ...
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39 views

Difference between “computational statistics” and “statistical computing”?

From Handbook of computational Statistics by Gentle et al, We use the term “statistical computing” to refer to the computational methods that enable statistical methods. Statistical computing ...
2
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1answer
86 views

MCEM algorithm in normal distribution

Consider $z_1,\ldots,z_n$ as a sample of observations of $Z$ and $y_1,\ldots,y_n$ the missing data, where $Z\sim N(\mu,\sigma^2+1)$ and $Y\sim N(0,1)$. i)Find the expression of ...
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0answers
42 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. ...
2
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1answer
67 views

What are the general methods for parameter estimation in statistics?

I have a task to estimate the probability of evolution selection of a given node. The only parameter estimation method I can think of is using the law of large numbers, i.e., use the proportion to ...
3
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1answer
142 views

An alternative to *The Statistical Sleuth*?

I will be starting graduate school in statistics in August. I purchased The Statistical Sleuth recently [you can view the table of contents by clicking on the "Look Inside" link], and I do think it is ...
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22 views

How to train a Gaussian Mixture Model using Testing Data

My work is to extract HOG features from Arabic Line images and than do classification using Gaussian mixture model to have a look at the performance. My question is after extracting the features how ...
3
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1answer
57 views

I am having trouble understanding EM gradient algorithm can someone help?

I understand the formula for the EM gradient algorithm but I don't understand what it means by taking one step of Newton's method. Does it mean that it just take one iteration to converge to the ...
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48 views

Generation of data 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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58 views

Median-computation (“grouped median”). Problem with gmedian-computation in SPSS

In my basic-statistics course I wanted to delve deeper into the problem of the (grouped) median-computation and did some computations using SPSS. The protocol seems to indicate either a different ...
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43 views

How to design an economic index?

I'm designing a linear economic index: $I_{t}=W_{1} X_{t_{1}}+W_{2}X_{t_{2}}+W_{3}X_{t_{3}}$ where $W_{1}$ to $W_{3}$ are weights of inputs ($X_{t_{1}}$ to $X_{t_{3}}$) and $I_{t}$ is the final ...
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3answers
87 views

Using KS test to evaluate differences

There are two different empirical CDFs which I have and I would like to evaluate how different they are. The place at which I started was Kolmogorov-Smirnov test - the result in my case looks like ...
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56 views

finding the interpolated values of an empirical probability distribution

I have an empirical probability function $p(z)$. In the first column $z$ and the second column contains $p(z)$ values. The data is given as following : data.cat ...
2
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1answer
39 views

computational considerations on the regression problems

I am reading Elements of Statistical Learning and read the following claim from the text (page 93, Chapter 3.7): Least squares fitting is usually done via the Cholesky decomposition of the matrix ...
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5answers
556 views

What algorithm should I use to detect anomalies on time-series?

Background I'm working in Network Operations Center, we monitor computer systems and their performance. One of the key metrics to monitor is a number of visitors\customers currently connected to our ...
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29 views

Is there any alternative to the EM algorithm?

I am working on biomedical signal analysis and the most used method for parameters estimation is the EM algorithm. My question is : what are the most powerful alternatives to this algorithm?
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18 views

Longitudinal data study and Analysis?

For doing an analysis with longitudinal dataset and to study the relationship between serial of observations of different subjects over unequally time spaced periods and to understand the relationship ...
2
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2answers
118 views

Double integral, monte carlo estimation

Suppose I have pairs of random variables where $X_i$~$U[0,1]$ and $Y_i$~$U[0,1]$ and I want to estimate it $$\theta=\int_{0.5}^{1}\int_0^{0.5}e^{xy}xydxdy$$ but $\theta$ needs to have variance less ...
2
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2answers
154 views

R random vector generator

Create an R function generating ordered pairs x,y sampled from the two dimensional distribution whose pdf is of the form $f(x,y)=cxy$, where $0<x,y<1$, and $c$ is a constant to be ...
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2answers
78 views

How to z-normalize multi-dimensional time series?

z-normalization for 1-dim time series is simple. $z_i = (x_i-m)/s$ Here, $x_i$ is the element of series for each time index $i$. $m$ is the mean, and $s$ is the standard deviation. For n-dim time ...
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0answers
12 views

How to chose the limit of speed for a stop

I have mouse events data(mouse events are generated when the mouse is moving). What would be the best way to calculate when the mouse is stopped? I see two cases: for ...
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25 views

How to distinguish histograms having two distinctive peaks?

I have two categories of histograms, one of them has two very distinctive peaks (not necessarily at the same bins/locations every time). What might be a good algorithm/method to find out such ...
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2answers
52 views

Interpreting kmeans output

I am working on a clustering model with the kmeans() function in the package stats and I have a question about the output. My data is a sample from several tech companies and AAPL._UP is a variable ...
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1answer
51 views

How to rank monthly data, using both trends and averages

I have a very large data set containing the daily searches for some Wikipedia entries. I am using the number of searches as proxy of popularity and want to rank the entries. Lets say I have entities ...
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1answer
58 views

Introductory examples in computational statistics class

I'm looking for an example of Bayesian inference for a class with the properties: The problem is easy to state, and the model & prior are both pretty reasonable, and R can't really calculate the ...
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2answers
43 views

Compare lists of genes

I have two lists of differentially expressed genes: the list 1 was derived from the universe A of total genes while the list 2 was derived from the universe B of total genes. A number of genes is in ...
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0answers
20 views

Is there any reason that cross correlation would perform well or poorly on sparse binary arrays?

I am using matlabs xcorr to correlate simulated photon count data that has some Gaussian random noise set on top of it and it is working fine when the average value in the arrays is greater than one ...
4
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1answer
62 views

Cholesky factorization and forward substitution less accurate than inversion?

I recently asked this question asking for an efficient way to compute the Mahalanobis distance (without calculating the inverse). The accepted solution was to use the Cholesky factorization and ...
2
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0answers
30 views

What is a statistically rigorous model? [closed]

Is there a formal definition for a model or methodology being statistically rigorous? I've seen the term often used in research papers but I've never fully understood what makes the model or method ...
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47 views
4
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1answer
271 views

Efficient/fast Mahalanobis distance computation

Suppose I have $n$ data points $x_1,\dots,x_n$, each of which is $p$-dimensional. Let $\Sigma$ be the (non-singular) population covariance of these samples. With respect to $\Sigma$, what is the most ...
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1answer
33 views

Calculation of Cosine Similarity using LSA

I am getting negative cosine similarity value between two documents in Latent Semantic analysis. How should it be treated?