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

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33 views

Kolmogorov-Smirnov(KS) statistic for multi class problems [on hold]

How to evaluate the performance of multi-class classification model using KS statistic? My goal is to evaluate the classification algorithms namely Random Forest,Logistic Regression and SVC using ...
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5 views

What is the spatial coupling in a random field? [closed]

What is the meaning of "spatial coupling of grid nodes" in a random field ?
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6 views

Confidence Interval for mean difference with non-mutually exclusive 1 to many matches in R

This is somewhat both a programming question, and a stats question. So sorry for the overlap (although it seems that there is a large overlap between the realm of stats and programming of ...
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16 views

Model choice for discrete data with R

I'm keen to model the effect (impact) of variable i.e. var1 and its effect (causation inference?) on var2 given the score measure. Sample data (variation of data I have got) ...
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15 views

Confusion on a term regarding an exponential random variable?

Let A be a random variable with a B parameter 2. I understand that this means the density function, D(X) = 2*Exp[-2A] However, for a computational statistics project, I was asked to: Simulate X = ...
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2answers
1k views

Mathematica's random number generator deviating from binomial probability?

So, let's say you flip a coin 10 times, and call that 1 "event". If you run, 1,000,000 of these "events", what is the proportion of events that have heads between 0.4 and 0.6? Binomial probability ...
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24 views

Scoring model/formula to rank based on accuracy of data sources

Let us say i have 5 different data sources. My aim is arrive a score to arrive the accuracy of this data sources. It is like below 1. Refer the section Data confidence calculation in ...
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1answer
94 views

Estimate mean & standard deviation of set S if I know stats of an inner set and outer set

Suppose I have sets $S_1\subset S_2\subset S_3$. I know exactly the size, mean, and standard deviation of both $S_1$ and $S_3$ and want to estimate the mean and standard deviation of $S_2$, where I ...
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29 views

What is first order asymptotic distribution?

I am stuck with this term in a research paper(Hansen, 1999). Its written (p 351) "Hansen (1996) shows that a bootstrap procedure attains the first-order asymptotic distribution, so p-values ...
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28 views

What are the quantitative methods alternative to Meta-Analysis?

What are the alternative statistical quantitative synthesis methods for combining studies, if we can't apply meta-analysis because of the heteronegeity or the shape of the data, for the data set of ...
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2answers
56 views

When is calculating probability based on a poisson distribution preferred over a binomial distribution?

I'm trying to understand why a poisson distribution may be preferred over a binomial one when modeling binary cases. Is there a case where you can't use a binomial distribution to solve a problem ...
3
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1answer
80 views

Find the expectation and covariance of a stochastic process

The problem is: Let $W(t)$, $t ≥ 0$, be a standard Wiener process. Define a new stochastic process $Z(t)$ as $Z(t)=e^{W(t)-(1/2)\cdot t}$, $t≥ 0$. Show that $\mathbb{E}[Z(t)] = 1$ and use this result ...
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2answers
34 views

Hierarchical Gamma-Poisson CDF?

What is the most computationally efficient way to evaluate the CDF $$P(X \leq x | r,v)$$ where $$ X \sim Poisson(\lambda)$$ and $$ \lambda \sim Gamma(r,v)$$ I can't see the next obvious step after ...
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1answer
58 views

Which statistical melhods could I use to determine if a price is good, based on a history of prices?

I have the following scenario: A history of prices of a specific product; The current price of the same product. The history of prices should contain prices with a certain amount of discount, very ...
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2answers
58 views

How to validate if a sample is independent and identically distributed

How can I check if the data is drawn i.i.d. from an unknown multivariate distribution?
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1answer
43 views

Similarity scoring to compare multi-dimensional datasets

I am trying to come up with a mechanism of scoring a set of multidimensional datasets based on a similarity with an ideal dataset. Each dataset will all have the same dimensions along with the ideal. ...
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58 views

R - system is computationally singular - dealing with small numbers

I'm working with a ~200x200 Markovian transition matrix of non-zero probabilities. Forcibly, these probabilities are, for the large part, going to be very small. I am trying to find the inverse of my ...
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11 views

Can one fuse graphical and quantitative techniques?

The NIST Engineering Statistics Handbook provides a great compendium of graphical and quantitative techniques. Every technique (graphical or quantitative) is usually explained with a set a questions. ...
3
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1answer
23 views

Data rescaling for a more informative heatmap?

I have a 2000$\times$2000 matrix of values. Over half of the values are 0, and for those non-zeros, most of them are less than 10, but the maximum value is 140. So when I do a heatmap, it looks like ...
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29 views

propagation of the error in the summation

I have a question regarding the propagation of the error during the summation. Please see the equation below. In this equation only quantity R has an error. How it will propagate to the final value ...
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1answer
44 views

What is the distribution of $X$ since $X|Y \sim \mathrm{Bi}(Y, p)$ and $Y \sim \mathrm{NB}(r, q)$?

I have done the usual steps to calculate the marginal distribution of $X$, i.e. using the following formula: $$p(X) = \int p(X,Y) dY = \int p(X|Y) p(Y) dY$$ Therefore, it holds: \begin{align} P(X=k) ...
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5 views

For an ANOVA comparing here treatment condition

a) None of these choices is correct. b) All three of the population means are different from each other. c) At least one of the three population means is different from another mean. d) There are no ...
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27 views

Convergence Time of the EM Algorithm Depending on the Inital Parameter Values

I try to get an intuitive understanding of the convergence properties of the EM-Algorithm. I wrote a code that does the following experiment. We are given three coins: $H$, $A$ and $B$; with ...
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1answer
38 views

measure for jobs/complaints ratio

I have a number of jobs in a database which can receive complaints. A job can receive several complaints and a job has an associated supplier. I would like to identify the worst performing suppliers. ...
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23 views

selection of features with Weka

I have a question and I hope that you can help me: I have a bilingual text(source language and target language). I extract from this text the best source phrase and the target phrase related to this ...
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136 views

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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28 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 ...
2
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1answer
208 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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26 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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0answers
7 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
52 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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19 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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23 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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15 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 ...
2
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0answers
32 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 ...
0
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1answer
57 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
42 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
85 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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0answers
123 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 ...
2
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2answers
422 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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0answers
23 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 ...
4
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1answer
89 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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18 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 ...
2
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0answers
27 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 ...
0
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1answer
202 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 ...
3
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0answers
57 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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25 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 ...
2
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1answer
116 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 ...