# All Questions

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### What will be the process of statistical analysis with Survey data?

I have the survey data of sales force satisfaction and dis-satisfaction . In this data set,there are three to five sub-questions inside to one question. I want to know how can i start the statistical ...
13 views

### Why are Bayesian classifiers “robust to noise”?

In many different settings I've read that Bayesian classifiers like Naïve Bayes and Bayesian Networks are more robust to noise in the input data than other classifiers. I'm wondering what the evidence ...
47 views

### Can R substitute PRIMER efficiently and effectively?

Quite a simple question, looking to see if anybody has experience using both. I have no knowledge of PRIMER, but wondering if R (currently) has the same capacity for data analysis specifically for ...
22 views

### How to perform K-medoids when having the distance matrix

I've been trying for a long time to figure out how to perform (on paper)the K-medoids algorithm, however I'm not able to understand how to begin and iterate. for example: I have the distance matrix ...
7 views

### Evaluating productivity metrics in an A/B test system

I'm beginning work on an A/B testing system for UX changes to a tool my team builds. Our users are doing simple, repeatable tasks assigned by another team's system. My team handles the UI/UX part. ...
10 views

### Calculating TF-IDF in Matlab for Stop Words

I have been calculating tf-idf for removing stop words in my file. I am experiencing problems. First let us have a look at code I have written.. ...
30 views

### R - How to convert from Mann-Whitney U to Z (or other effect size )?

I'm looking at multiple studies. I do not have the original data. One study I'm looking at provides means, standard deviations, and Mann-Whitney U values (with p). (How) can I convert from ...
29 views

### How Can I Make Sure All My .CSV Data Gets Imported as NA instead of Blank in R? [migrated]

In my dataset, I'm using have four assessments I'm trying to predict: 1 [Good] to 4 [Bad]. My model seems to be working using the polr function to predict values ...
59 views

### Help for planning a neuroscience experiment

I'm new here. I am planning a neuroscience experiment. I will be measuring brain signals from about twenty subjects. I will present the subjects four different kinds of stimuli. After all the data ...
30 views

### How can I analyze my incoming email?

I would like to analyze the email I receive in my Gmail inbox in order to systematically come up with effective Gmail filters for the most common types of email. I am prepared to manually curate and ...
34 views

### Which error is displayed in an error ellipse?

I have some bivariate data and I have calculated the error ellipse in the following way: I have first calculated the covariance matrix and then to obtain the radii of the ellipse I have taken the ...
75 views

### 2 sided vs 1 sided test

I am asking this questions straight from "Data Analysis and Statistical Inference " course by Dr. Mine Çetinkaya-Rundel on coursera! Please right click on the image and one in a new tab to make it ...
31 views

### Classification Accuracy

I am classifying text based on news headlines and I am achieving accuracy up to approx 80%. I want to improve it more. But issue is that when I calculate the same with synonyms using the code below: ...
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### Statistical Practices Using Sparse Data: Methods for Approximating Standard Deviation

Suppose I know that for a discrete, non-negative r.v. $X$ that $X | X \geq 1$ has $\mu = 3.3$ while when $X \geq 0$ has $\mu = 2.1$. That is, the subset of the population that already has a value ...
15 views

### Tutorial on Radial Basis Function Networks?

I want to learn about Radial Basis Function Neural Networks, can you please suggest a good introduction or tutorial? All the introductions I found are rather short or incomplete or so.
18 views

### How to interpret the coefficients and plot the relationship between IV_i and DV?

I'm using Tobit regression and I'm not sure how to interpret the coefficients. I made sample data with random function in Excel. ...
95 views

### Why is the Pearson correlation 1 when only two data values are available?

I am trying to obtain a Pearson correlation between 6 different variables (represented by columns in the matrix below) with two datapoints each (rows). This is the matrix: ...
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### Is it possible to run Arellano-Bond estimator when i have three time periods?

I have a hard time figuring out if I can use Arellano-Bond GMM when I hahve 3 time periods. In the first period there is 37 observations, 47 in the second period and 60 in the thrid period. However, ...
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### Dynamic conditional correlation DCC subscrip invalid function return error

I have two series as standardized residuals generated from arch(1) garch(1): ...
21 views

### Bayesian mean square error

Given a i.i.d sample $X_{1},..,X_{n}$ of bernoulli random variables test 2 hypotheses $H_{0}:p=2/3$ and $H_{1}:p=1/3$. Bayesian prior is $\pi(2/3)=1/3$ and $\pi(1/3)=2/3$. Find the bayesian criterion ...
13 views

### Rigorous Bell-CHSH?

The usual derivations by physicists of the Bell-CHSH inequalities as a limit imposed on any possible local hidden variables description of quantum systems seems so sloppy, that I'm tempted to ask you ...
18 views

### Detecting heterogeneity in groups

This is a mockup of a dataset I am currently working on: ...
27 views

### Forecasting discrete non normal data

Today I was thinking about how one would treat what I'm guessing must come up constantly in statistics so apologies if it's trivial. Some statistics such are easy to forecast, such as length, thanks ...
11 views

### number of stochastic nodes in bayesian multivariate distribution?

I'm doing some bayesian modeling using BUGS - JAGS to be specific. I find it hard to infer how many stochastic (i.e. non-deterministic) nodes there really are when I use multivariate distributions. ...
30 views

### Fixed / Random Effects Model

I have the following kind of panel data set, without a time variable. 20 countries are the panel variable and provide data on 48 other countries. The independent variables are 6 (intercorrelated) ...
1k views

### What does 'highly non linear' mean?

I often read about a function being 'highly non linear'. In my understanding, there is "linear" and "non-linear", so what is this 'highly' about? Is there a formal difference from non linear? How is ...
26 views

### simulating distributions with non-symmetrical confidence intervals in R

I have a software package that outputs estimates that have non-symmetrical confidence intervals. I am simulating these distributions for further Monte-Carlo estimates. In the below example I am trying ...
14 views

### clustering of singular values

let us consider following graph of singular values i want to make some kind of clustering of these data,namely to seperate main components from non main components,let say signal components ...
10 views

### Does Boruta feature selection (in R) take into account the correlation between variables?

I am a bit of a novice in R and feature selection, and have tried the Boruta package to select (diminish) my number of variables (n= 40). I thought that this method also took into account the possible ...
260 views

### What is the difference between multiple regression & mutivariate regression?

I have data on GDP growth as a dependent variable and growth in main production sectors of Pakistan such as mining, electricity, communication, manufacturing and electricity. I am supposed to run a ...
13 views

### Datasets for some popular books

I'm looking for electronic versions of datasets used in examples and exercises from the following books: Aczel "Complete business statistics" Milliken & Johnson "Analysis of Messy Data" vol.1 ...
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### Interaction in Survival analysis

I am a physician and clearly not a statistician (I try to understand why and how to perform the right analysis, but I don't understand the formulas). I am using SPSS v.19 in analyzing my data. I try ...
26 views

### Expectation of Truncated & Random Variable

I have what appears to be a relatively simple question, but am struggling to understand how to go about answering it. The general question is as follows: What is the expected value of $S_{I}$, ...
13 views

### Determining the uncertainty of an exponential fit

My problem should probably be built up from the beginning, so lets start there. I performed a certain experiment 25 times. Every time, the experiment consists of 5000 measurements, and each ...
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### Difference between ep-SVR and nu-SVR (and least squares SVR)

I am trying to find out which SVR is suited for what kind of data. I found out 4 types of SVRs: epsilon, nu, least squares and linear. I understand linear SVR is more or less like lasso with L1 Reg. ...
17 views

### Difference test between 2 groups where both groups contain depended and independent observations

Is there a statistical test to check the difference between groups (for example a paired sample proportion test), but where some of the observations of the two groups are dependent and some of the ...
14 views

### Feature Selection for look alike modeling using k-NN

I have a list of items(around 7000) and various parameters for each items. For each item on my list i need to identify 10 items which are similar to the item from my whole population (17 million). I ...
39 views

### Offset variable in Poisson regression makes model worse

I'm using a Poisson regression to model count data (number of orders). My observation lengths are different, so I tried to include an offset variable in the model. The problem is that when I estimate ...
30 views

### How to compare two different clustering approaches?

I'm making a project connected with identifying the dynamics of sales. My database concerns 26 weeks (so equally in 26 time-series observations) after launching the product, 126 time-series=126 ...
20 views

### Standard deviation of several measurements with uncertainties

I have two 2 hours of GPS data with a sampling rate of 1 Hz (7200 measurements). The data are given in the form (X, X_sigma, Y, Y_sigma, Z, Z_sigma), where N_sigma is the measurement uncertainty. ...
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### What does changing the time-frame of the dependent variable tell me?

I have a question concerning a cross sectional regression model. I want to know how to interpret the change in the explanatory variables gathered from a base year (say 2005) when I replace my observed ...
44 views

### Meaning of Qqnorm plot in R

I am testing the normality of a sample with R using qqnorm. I obtain this: I understand that the meaning of this plot is that the sample has fat tails. But what is the meaning of the values on the ...
37 views

### PCA on non-centered data [duplicate]

How does the mean influence PCA? What happens if I use PCA on data with a mean $\ne0$?
28 views

### How to interpret Weka logistic regression output for a nominal attribute and its coefficients? [on hold]

Kindly help me interpreting the output of logistic regression in Weka. I have a data set. Below is the arff file. There is one numeric attribute and 3 nominal ...
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### Observed versus Synthetic data

I am looking for studies that compare different spatial interpolation methods for observed data. However I am looking for studies that have also compared observed with generated synthetic data. For ...
16 views

### How to compare forecasting methods: based on ARIMA and curve fitting?

I'm making a project connected with identifying the dynamics of sales. My database concerns 26 weeks (so equally in 26 time-series observations) after launching the product. I want to make forecast ...
51 views

### Differences in edition of advanced statistics books

In general I'm wondering if there's any danger in studying from older edition statistics books. The undergrad material seems to have remained unchanged throughout the last century, but I'm looking for ...
4 views

### How to train input feature weights for a path optimization problem?

I am working on a general path optimization problem. As many of you know, once the weights on all nodes are determined, one may solve this problem in many different means. Unfortunately, my raw input ...
I have a system with the following structure: $X_{t+1} = X_t + E_{t+1}$ $E_{t+1} \sim N(0, \Sigma)$ $Y_{t+1} = f(X_{t+1})$ $Y_{t+1} \sim {\rm Uniform}(a_{t+1}, b_{t+1})$ So $X$ is a vector of ...