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

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33 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
17 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 ...
2
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1answer
48 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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0answers
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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0answers
15 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
48 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
42 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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0answers
12 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
21 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
36 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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0answers
19 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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0answers
19 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 ...
0
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1answer
30 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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0answers
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
201 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 ...
0
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2answers
31 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 ...
0
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0answers
13 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. ...
2
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2answers
311 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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0answers
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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0answers
30 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
81 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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0answers
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 ...
5
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1answer
48 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 ...
0
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1answer
24 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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0answers
75 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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0answers
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 ...
4
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3answers
191 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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0answers
17 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: ...
0
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1answer
15 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 ...
3
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2answers
168 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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0answers
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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0answers
29 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 ...
0
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0answers
64 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: ...
0
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0answers
43 views

The correct way to do Cross-Validation

Consider the case that I need to do cross-validation for SVM to obtain a good estimate of the cost parameter $C$. I am not sure when should I divide the data into $K- $ folds. To perform the ...
0
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1answer
60 views

What are the general strategies in creating a Probabilistic Graphical Model?

While there is lot of theory and probability in the background to understand, I wanted to know if there are any resources/quick pointers on what to consider while modeling a problem using Bayesian ...
1
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1answer
95 views

time series — seasonal adjustment

I'm concerned to seasonal adjustment procedure and want to know the criteria for this purpose can anyone please give me the answer of the following question. what should be the criteria for seasonal ...
0
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0answers
64 views

Interpretation of TBATS Components

I've searched everywhere for this answer, and come up empty handed. I'm building a forecasts model for interface traffic reported in 5 minute intervals over a 1 year period. To account for ...
8
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1answer
107 views

Nonparametric mixture model and clusters

I have a question about clusters that I am contemplating to treat with a nonparametric mixture approach (I think). I am working on the explanation of human comportment. Each row of my database ...
0
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1answer
49 views

Smoothing Spline Example

I am learning the smoothing spline method. I saw that smoothing spline is a penalty term to reduce overfitting in linear regression. Given dataset {$(x_1,y_1),(x_2,y_2)..(x_n,y_n)$}So the formular ...
1
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1answer
174 views

How do we define log-normal prior and a multivariate posterior log-likelihood in PyMC?

I am a newbie with pyMC and I am not still able to construct the structure of my MCMC with pyMC. I would like to establish a chain and I am confused how to define my parameters and log-likelihood ...
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0answers
39 views

Mediation using 'mediate' in R with an interaction

I have a question about mediation when there is an interaction between 2 categorical variables, one with two levels and one with three levels. Using the ‘mediation’ package by Tingley and colleagues ...
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0answers
22 views

What's the best approach to statistically analyze announcements on the price of a stock?

I have stock price data from Yahoo and I have corporate announcements from various RSS feeds that give me the date of the announcement, the date of the quarterly statement, etc. What is the best ...
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1answer
73 views

Best tutorials for R beginner? [duplicate]

Heyo- I just started fooling around with R and want to find a good tutorial. Suggestions? Also, are there other things I should be doing to beef up my R chops? Context: very little coding ...
0
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1answer
44 views

Categorical Data with multiple categories (variable selection)

I have a model with multiple categories for several categorical variables. I'm interested in prediction. So far I've been using step(). The issue with it is that it doesn't treat variables with ...
0
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0answers
65 views

Piecewise nonlinear regression by MLE in R software

I have been working with nonlinear models whose parameters have been estimated by Maximum Likelihood. Also, I use the "Vuong" test for model selection in non-nested models, this test requires to have ...
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0answers
70 views

Fitting multiple logistic functions at once with pymc

I have read a similar post here Fitting logistic function with pymc but it seems there is a rule that I shouldn't ask question in someone else's post. My approach is to fit 10 logistic functions to ...
1
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1answer
83 views

Constructing one-ninth fraction of the $3^{5}$ design

I want to construct a $3^{5-2}$ design with $I=ABC$ and $I=CDE$ as generators. The complete defining relation for this design is: $I=ABC=CDE=ABC^{2}DE=ABD^{2}E^{2}$. This is a resolution III design ...
1
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1answer
53 views

How to make sense of 6mo worth of weight loss data?

-I have ~6mo of data that contains daily weight/caloric intake & #carbs/fats/proteins. I'm trying to figure out a way to make sense of the data. It's not a perfect experiment so there are other ...
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0answers
272 views

How to interpret the LDA output in R?

Basically, I have following LDA output (below). My question is how do I actually interpret it ? I could not find much resources on the web. Especially, what does "Group Means" really mean here ? I was ...
5
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3answers
98 views

Given two sets, how can I say statistically if they are similar/different

This is a very open ended question. Suppose I have two sets of data samples of the same form, say [item, rating]. Rating is a value on the interval [0,100] and item is a unique identifier given to a ...