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

learn more… | top users | synonyms

0
votes
0answers
15 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 ...
0
votes
0answers
22 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 ...
1
vote
4answers
71 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 ...
0
votes
0answers
7 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
votes
1answer
45 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
votes
1answer
23 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 ...
0
votes
0answers
38 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 ...
0
votes
0answers
7 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
votes
3answers
156 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 ...
0
votes
0answers
8 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
votes
1answer
14 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
votes
2answers
96 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 ...
0
votes
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?
1
vote
0answers
27 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
votes
0answers
29 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
votes
0answers
37 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
votes
1answer
43 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
vote
1answer
60 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
votes
0answers
34 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
votes
0answers
92 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
votes
1answer
40 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
vote
1answer
113 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 ...
0
votes
0answers
24 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 ...
0
votes
0answers
21 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 ...
-2
votes
1answer
66 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
votes
1answer
34 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
votes
0answers
48 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 ...
0
votes
0answers
50 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
vote
1answer
82 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
vote
1answer
49 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 ...
0
votes
0answers
169 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
votes
3answers
88 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 ...
1
vote
0answers
30 views

Condition number of covariance matrix

I am interested in generating a covariance matrix of dimension say 100. I managed to get a correlation matrix with finite condition number. To construct a covariance matrix I need to have standard ...
0
votes
1answer
68 views

Basic R script/package with lots of automated calculations [closed]

Does that exist? A basic R script or package that just needs the data, and it spits lots of “basic” statistics (like the mean, the median, quartiles, make a plot, a boxplot, a histogram, a cumulative ...
5
votes
1answer
95 views

Advice on sensitivity analysis for priors in Bayesian statistics

I'm not clear on how to perform sensitivity analysis on the priors. Many sites have different answers. One site indicates to perform three non-informative, weakly informative and known priors. Another ...
0
votes
0answers
19 views

What are the advantages of using a Neural Network to impute data?

What are the advantages and drawbacks of using neural network methods to impute data? Is the bias and total error any higher than other methods (e.g., median or mean method, nearest neighborhood, or ...
0
votes
1answer
97 views

What is SVM regression? Is it for regression or classification?

I'm trying to understand what is SVM regression. It's used for classification or regression? Can someone give an intuitive understanding of it?
0
votes
0answers
22 views

Levenberg-Marquardt adjustment

I understand that Levenberg-Marquardt adjustment is about adding $\lambda \times\; I$ to second derivative of the log likelihood function, where $I$ is the identity matrix $$-[l''(\theta | Y) - ...
0
votes
0answers
31 views

Project in Bayesian biometrics

I'm working on a project about specific bird species on an island in the Northern Atlantic sea. The data seem reliable and pretty detailed, and range from the 18th century, however their structure and ...
1
vote
0answers
19 views

Newton Raphson Algorithm: negative semi definiteness [duplicate]

I would like to minimise the function $l(\theta|Y)$. Given the Newton's method below $$\theta^{(t+1)} = \theta^{(t)} - \left[l''(\theta\;|\;Y)\right]^{-1} l'(\theta^{(t)}\; | Y)\quad t = 0,1,...$$ ...
1
vote
0answers
19 views

How to extract “average polyline” from a set of polylines [duplicate]

EDIT: As pointed, there is already a similar question "buried" inside a larger-scope one. I'll reproduce the relevant part here: If I have multiple recordings of the same routes are there any ...
0
votes
1answer
82 views

How to calculate the probability of winning an election?

I'm analyzing a survey data that contains the following 3 variables (questions): If the election was today who would you vote for in the following list? (A, B, C, D, or E)? Let's imagine the ...
0
votes
1answer
76 views

Probability of webpage accessed in a particular hour

I want to programatically calculate at which particular hours of a day the probability of a webpage hits(accessed) are high. Which statistic formula should I use to calculate the peak hours of the ...
0
votes
1answer
77 views

Computation of a binomial probability: nan result

I am computing binomial probabilities for many parameters. I am using the library scipy.stats: b = scipy.stats.binom(n,p) probability = b.pmf(k) I have noticed ...
1
vote
2answers
45 views

Sampling from low probability regions

I have a pdf that I need to sample from, but I'm having numerical issues and was hoping someone could provide some insight. My pdf is a product of gaussians $$ P(\theta |d ) = \prod_{i=1}^{N} C_{i} ...
3
votes
1answer
157 views

Statistics for Area under the ROC curve

I have a question regarding statistical evaluation of the AUC. In their paper (http://www.jstor.org/stable/2531595), DeLong et al. describe a method to evaluate AUC curves. (Another good explanation ...
1
vote
0answers
22 views

Statistical method to map a set of values to another

I am completely newbie to stats. And I want to know which statistical method would be applicable for following scenario. I have a bunch of sentences extracted from a text document. Each sentence has ...
1
vote
0answers
37 views

Finding the equation for a data set

I asked this question on StackOverflow and someone pointed for me to ask this here. Lets assume that I have 3 variables: x, y, z which are integers. I have 5000 values of each and I want to predict ...
1
vote
1answer
264 views

Why is the lower limit of my lower 95% confidence interval negative?

I'm conducting some research related to the use of patient data and quality of care. I'm generating a linear regression graph between phone bill size and customer population. Assume that the intercept ...
0
votes
0answers
26 views

Non linear maximization problem

I am not sure how I can solve this optimization problem. I have a (MATLAB) code which can solve this but only for very low dimensions, that is, low values of $n$ (around $n = 4$ or $5$), once $n$ ...