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

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Is it correct or not I applied PERMANOVA-test and interpreted results?

I want to associate nutrients with microbiota bacteria composition. My data consist of two tables: nutrient table (row - patients, column - some of nutrients, e.g. protein, calorage); bacterial ...
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20 views

Sampling Size for a large Dataset

I am having a dataset of size upwards of 200 million rows. I have no knowledge of the distribution of this dataset. Would like to perform some analysis on this - like look at the ...
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24 views

What statistical analysis to use?

What statistical analysis should I use if I have 2 groups of subjects (high and low comprehenders) which are divided into 3 subgroups according to text genre (poetry, short story, drama) and subjected ...
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1answer
188 views

Area within a given number of standard deviations from given mean

I have a variable with mean value of 18.85 and standard deviation of 1.45. I want to define the area that is covered by 1.45 standard deviations left and 1.45 standard deviations on the right side ...
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3 views

making for making dataset for spam classifier

I'm trying to make a dataset for spam detection, what is the best automatic selection that I can use for picking up the word that should i count for my spam base ? Thank you
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18 views

Fast way to compute central moments of a Poisson random variable?

I am looking for a way to quickly compute the central moments of a Poisson random variable. I've found a couple of resources on how to compute the central moments, but I'm still trying to figure out ...
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6 views

how do i differentiate between alternative specific and alternative invariants using sas?

Okay so my level of expertise in statistics is fresher/rookie. I am trying to predict the the outcome of categorical choices for a product category y (3 choices or 3 flavors of cereal for example). ...
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1answer
36 views

What statistical analysis should I use for my study?

In my psych class we were testing to see if groups of men or groups of women would be more helpful in an emergency situation (we are testing for the bystander effect), and we are testing to see if ...
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8 views

Matching sets of 3d position data

Imagine a cube filled with air and ~5000 levitating potatoes. The distance between two poatatoes are usually at least an order of magnitude larger than their volume and their distribution is pretty ...
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11 views

When is appropriate to combine two treatment groups from one study into a composite whole for a meta-analysis?

The treatment groups I would like to combine appear to be virtually the same, at least by generic label for each group, e.g., groups with the same treatment but implemented at different sites or ...
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9 views

Need Insight on Measuring Variable Effect

I apoligize in advance for the wall of text. I'm working on a project in which I have been asked to determine what factors influence employees leaving our company. Also, it would be useful to be able ...
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26 views

Aggregate variance for ordinary least squares?

I am writing some MapReduce code to calculate ordinary least squares from a sample of data. I'd like to include standard error, but I am running into a problem in calculating the variance of the ...
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1answer
46 views

Outliers In Predicted Intervals

In my stats class today, the professor was showing us some output from MINITAB on a prediction interval that was calculated (from time series data). For one of the prediction intervals, MINITAB had an ...
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1answer
39 views

Is it possible to combine several clustering results in a meaningful way?

The problem I face is somewhat awkward, I have 40,000 points in my dataset and I would like to cluster them hierarchically. But due to the limitation of my laptop(and R) in each run of clustering only ...
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1answer
46 views

How to solve this problem on Curse of Dimensionality problem - Nearest Neighbours

I have started learning classification techniques and trying to solve the problems from the book Introduction to Statistical Learning. While currently working on the which is based on Curse of ...
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30 views

What do the dip test output parameters mean?

This may sound like a silly question, but I'm not a statistician, mathematician, or programmer, really. I did quite a bit of googling, including looking into Stack Exchange, but couldn't find a clear ...
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2answers
98 views

Time Series Anomaly Detection with Python

I need to implement anomaly detection on several time-series datasets. I've never done this before and was hoping for some advice. I'm very comfortable with python, so I would prefer the solution be ...
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22 views

Better calculation of ends of the curve when using R's RandomForest?

I've been using R's randomforest library to predict a series of (2000) products with prices ($10-$2000) and I'm noticing the low and high ends of the continuum are least accurate, especially when I ...
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1answer
58 views

Outlier Detection in Time-Series: How to reduce false positives?

I'm trying to automate outlier detection in time-series and I used a modification of the solution proposed by Rob Hyndman here. Say, I measure daily visits to a website from various countries. For ...
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17 views

A problem related to Dice [duplicate]

Alex has N dice; each of them has K faces numbered from 1 to K. Now he has arranged the N dice in a line. He can rotate/flip any die if he wants. How many ways he can set the top faces such that the ...
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20 views

Is there an efficient algorithm for sampling from the negative hypergeometric distribution?

I'm writing a small statistics library currently. One of the algorithms I'm implementing has two variants: one that samples the hypergeometric distribution and one that samples the negative ...
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1answer
76 views

CHAID decision tree - Binning continuous variables

I am running a CHAID classification tree on SPSS to classify my data set. I have a couple independent variables including categorical and continuous ones. For continuous variables, I've noticed that ...
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49 views

Is this problem Bayesian? And can I use variational approximation?

Suppose there are $N$ samples of observations $\mathbf X(n)$ ($n=1,\cdots,N$), which are given by probability distribution $p(\mathbf X(n)|\mathbf Z(n))$ with their conditions are given by hidden ...
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17 views

Writing the null hypothesis for ANCOVA

I have a dependent variable (scale data) called posttest, also an independent variable (nominal) of teaching method that has four levels. The covariate is the pretest measured at the scale level. I am ...
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1answer
25 views

Is there a way to estimate the distribution from only a small number of outliers?

For example, I was looking at this list of the 93 people who have broken the "10-second-barrier", after reading that sprinter Christophe Lemaitre was the first person of purely European decent to ...
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1answer
52 views

Can we run a chi squared test on a normalized function?

Hi I am fit a maxwell distribution and attempt to find the chi squared value in two cases: When the data is normalized. When the data is un-normalized. My problem is that the two ...
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20 views

How to check independence from empirical data

Let we've empirical data of two random variables X and Y. We can estimate empirically the degree of correlation between the two random variables by observing their scatter diagram, for instance. ...
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21 views

Identifying the number of conditions by which variance components will be divided in Generalizability Theory using QME R package

I'm using QME R Package (can be downloaded from here) to calculate Generalizability ...
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1answer
31 views

Resources for Computational Algorithms

The journal Applied Statistics used to have a section on algorithms, which are available online. Griffiths and Hill also published a selection of these algorithms in a book in 1985. But I can't find ...
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15 views

Categorical Missing Value Replacement

I want to ask how I could replace categorical missing values with reference please?
4
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1answer
204 views

Is there a convenient form for this large covariance matrix?

Consider the following bivariate vector autoregression: $$X_t=\mu +X_{t-1}A+\varepsilon_t,\ \varepsilon_t \overset{iid}{\sim} MVN(0, V),\ X_t=(X_{1,t},X_{2,t})',$$ where the assumptions on the ...
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2answers
38 views

Comparison between Two Groups

One of my demographic variable is age. Age is measured as continues data not categorical. If I want to test differences between two groups to determine whether there is significant difference between ...
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15 views

Response Rate in Research

I want to ask about response rate. I have distributed 2500 posts. However, I have received back around 30. Then, I sent 200 posts as reminders with appealing letter. I have received one or two only. ...
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2answers
320 views

How to transform a normal random variable such that I can simulate normal samples between the range of 1 and 45?

How to transform a normal random variable such that I can simulate normal samples between the range of 1 and 45? Do I need to do a jacobian transformation ?
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18 views

Selecting from a bigger control group for 1:1 ratio

What I have is a treatment group consisting of 90 individuals. I have a pool of individuals eligible for my control group, which I want to be matched by age and gender in a 1:1 ratio. Is there any ...
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33 views

How does a GAM scale with increasing number of knots, predictors, and observations?

I want to fit large Generalized Additive Models, and would like to know how the estimation scales, i.e. how much longer fitting the model takes when increasing the number of knots by 1, when adding ...
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4answers
87 views

Algorithm for rating books: Relative perception

So I am developing this application for rating books (think like IMDB for books) using relational database. Problem statement : Let's say book "A" deserves 8.5 in absolute sense. In case if A is ...
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8 views

How to handle edge cases in instant runoff voting?

I want to make forum software with instant runoff voting instead of polls, but I don't know what to do in edge cases. Should I allow voters to not weigh certain choices at all? If there are 5 choices ...
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1answer
50 views

Advantage of multiple simulations in old-fashioned Monte Carlo?

The spirit of this question comes from "Ordinary Monte Carlo", also known as "good old-fashioned Monte Carlo" Suppose I have a random variable $X$, with $$\mu := E[X]\\ \sigma^2:=Var[X] $$ Both are ...
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1answer
25 views

Alternatives to absolute error?

Let me explain my scenario in which I need to calculate absolute error. Lets say the X is the actual value. And X' is the value of X with some error 'e'. So X' = X + e'. Lets say i = 1 to 10000. I ...
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91 views

Analyzing neuralnet functions in R

The 'neuralnet' package in R allows us to use neural network algorithm with backpropagation. I want to use the function for prediction. I saw a tutorial on neuralnet in which predictions on the iris ...
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11 views

saturated structural equation model

I have a problem with SEM claiming to be saturated where it actually should test for missing covariances I am running a SEM composed in the following way. The ones with “2” behind are quardratic ...
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3answers
223 views

Is it possible in R (or in general) to force regression coefficients to be a certain sign?

I'm working with some real world data and the regression models are yielding some counterintuitive results. Normally I trust the statistics but in reality some of these things can not be true. The ...
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18 views

Regularization in multinomial manifold (k-simplex) space

I have a multi-class classification problem. In order to reduce the feature space, I have mapped my weights ($w$) to a multinomial manifold (or k-simplex) and compute the new weights ($v$) as follows: ...
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1answer
16 views

Solving feature bias issues in Learning to Rank with implicit feedback

I have a learning to rank system where implicit feedback (from user clicks) is used to determine +ve and -ve examples for the training. The problem is that (obviously) the learner sees only the top ...
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2answers
190 views

How to find optimal values for the tuning parameters in boosting trees ?

I realise that there are 3 tuning parameters in the boosting trees model, i.e. the number of trees (number of iterations) shrinkage parameter number of splits (size of each constituent trees) My ...
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15 views

How do I compare means of the same group on two continous variables?

I would like to compare the means of the same group on two continuous scales. I want to see if the scores are significantly different on the scales. Which statistical test do I use for this?
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31 views

What method(s) should I use to achive statistical ranking?

I'm attempting a project where I need to statistically rank available cars based on several variables such as cost, mpg, seating, milage, etc.. I wish to rank these cars in order decide which car ...
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84 views

How to handle the error of glmnet package for non-positive lambda?

I'm using glmnet package to learn regression models,it works fine, but for some models, I face an error and my script stops running. Here is my effort: ...