# All Questions

134,595 questions
744 views

### Elasticities Using GLM

The coefficient on a logged explanatory variable when the dependent variable also is in log form is an elasticity (or the percentage change in the dependent variable if the explanatory variable ...
142 views

### What statistical model is used to calculate the test results for GWO?

Google Website Optimizer (GWO) is a tool provided by Google to do A/B and MVT experiments on websites. This has been an unanswered question for a long time so I thought I'd ask it here and see if I ...
501 views

### Regression output and Fisher-Snedecor distribution

I'm working on regression models in STATISTICA application and I need to know what is Fisher-Snedecor distribution for and how to analyze my regression model in this distribution. What the ...
4k views

### Comparing the variance of paired observations

I have $N$ paired observations ($X_i$, $Y_i$) drawn from a common unknown distribution, which has finite first and second moments, and is symmetric around the mean. Let $\sigma_X$ the standard ...
3k views

### R lrm model with no predictors

I am creating multiple logistic regression models using lrm from Harrell's Design package in R. One model I would like to make is the model with no predictors. For example, I want to predict a ...
10k views

### What is AIC? Looking for a formal but intuitive answer

I've heard that AIC can be used to choose among several models (which regressor to use). But i would like to understand formally what it is in a kind of "advanced undergraduated" level,which i think ...
8k views

### Any suggestions for making R code use multiple processors?

I have R-scripts for reading large amounts of csv data from different files and then perform machine learning tasks such as svm for classification. Are there any libraries for making use of multiple ...
137 views

### How can I link item by relevance?

I am building a web application for used book trading and I am adding a feature to propose other book that would be interesting when they view an offer. Currently the data that I store are the ...
2k views

### What is the difference between functional data analysis and high dimensional data analysis

There are a lot of references in the statistic literature to "functional data" (i.e. data that are curves), and in parallel, to "high dimensional data" (i.e. when data are high dimensional vectors). ...
6k views

### When should normalization never be used?

Lately, there have been numerous questions about normalization What are some of the situations where you never ever ever should normalize your data, and what are the alternatives?
936 views

### How do I calculate the SE for PPV, NPV, and DOR?

I am attempting to calculate the standard error (SE) for the positive predictive value (PPV), negative predictive value (NPV), and diagnostic odds ratio (DOR) that I have obtained using the rates of ...
144k views

### Calculating optimal number of bins in a histogram

I'm interested in finding as optimal of a method as I can for determining how many bins I should use in a histogram. My data should range from 30 to 350 objects at most, and in particular I'm trying ...
1k views

### Normalization of series [closed]

I have data compiled by someone else where score averages have been computed over time- averages range from 0-100. The original scores have negative values in many cases and the average would have ...
4k views

### Why (or when) to use the log-mean?

I am looking at a scientific paper in which a single measurement is calculated using a logarithmic mean 'triplicate spots were combined to produce one signal by taking the logarithmic mean of ...
2k views

### Normal distribution and monotonic transformations

I've heard that a lot of quantities that occur in nature are normally distributed. This is typically justified using the central limit theorem, which says that when you average a large number of iid ...
5k views

### Operations research versus statistical analysis?

What is the difference between operations research and statistical analysis?
323 views

### Is it possible to use machine learning as a method for learning stats, rather than vice-versa?

During every machine learning tutorial you'll find, there is the common "You will need to know x amount of stats before starting this tutorial". As such, using your knowledge of stats, you will learn ...
298 views

### What types of data analysis do not count as statistics?

When does data analysis cease to be statistics ? Are the following examples all applications of statistics ?: computer vision, face recognition, compressed sensing, lossy data compression, signal ...
5k views

### Linear Mixed Effects Models

I have commonly heard that LME models are more sound in the analysis of accuracy data (i.e., in psychology experiments), in that they can work with binomial and other non-normal distributions that ...
785 views

### Use of Bayesian Search Theory in geological interpretation

I was having a look round a few things yesturday and came across Bayesian Search Theory. Thinking about this theory led me to think about a problem I was working on a few years ago regarding ...
126k views

1k views

### Suggested R packages for frontier estimation or segmentation of hyperspectral images

An hyperspectral image is a multidimensional image with more than 200 spectral bands i.e. an image for which each pixel is a vector of dimension 200 (most often it is a sampled spectral curve that is ...
5k views

### How can I test whether my clustering of binary data is significant

I'm doing shopping cart analyses my dataset is set of transaction vectors, with the items the products being bought. When applying k-means on the transactions, I will always get some result. A random ...
2k views

### Dataset for multi class perceptron

I am developing a multi-class perceptron algorithm and was wondering if there are any datasets that could be used to test a multi-class perceptron? - A dataset where the classes are linearly separable ...
5k views

### Data anonymization software

Is anyone aware of good data anonymization software? Or perhaps a package for R that does data anonymization? Obviously not expecting uncrackable anonymization - just want to make it difficult.
367 views

### How do I determine if a survival model with missing data is appropriate?

Oversimplifying a bit, I have about a million records that record the entry time and exit time of people in a system spanning about ten years. Every record has an entry time, but not every record has ...
387 views

### Lies, Damn Lies and Statistics [closed]

Is there something about statistics that lends itself to this sort of saying, or is it just that people will say anything to support their case, and this includes citing irrelevant or incomplete ...
13k views

### What is Bayes' theorem all about?

What are the main ideas, that is, concepts related to Bayes' theorem? I am not asking for any derivations of complex mathematical notation.
68k views

### What's the difference between probability and statistics?

What's the difference between probability and statistics, and why are they studied together?
1k views

### Automating statistical correlation between “texts” and “data”

I am collecting textual data surrounding press releases, blog posts, reviews, etc of certain companies' products and performance. Specifically, I am looking to see if there are correlations between ...
32k views

### Best books for an introduction to statistical data analysis?

I bought this book: How to Measure Anything: Finding the Value of Intangibles in Business and Head First Data Analysis: A Learner's Guide to Big Numbers, Statistics, and Good Decisions What ...
5k views

### Best ways to aggregate and analyze data

Having just recently started teaching myself Machine Learning and Data Analysis I'm finding myself hitting a brick wall on the need for creating and querying large sets of data. I would like to take ...
3k views

### How do you convey the beauty of the Central Limit Theorem to a non-statistician?

My father is a math enthusiast, but not interested in statistics much. It would be neat to try to illustrate some of the wonderful bits of statistics, and the CLT is a prime candidate. How would you ...
6k views

### Where is a good place to find survey results?

Sites like eMarketer offer general survey results about internet usage. Who else has a big set of survey results, or regularly releases them? Preferably marketing research focused. Thanks!
2k views

### Calculating ratio of sample data used for model fitting/training and validation

Provided a sample size "N" that I plan on using to forecast data. What are some of the ways to subdivide the data so that I use some of it to establish a model, and the remainder data to validate the ...
1k views

### Incorporating boolean data into analysis

I have a data set of about 3,000 field observations. The data collected is divided into 20 variables (real numbers), 30 boolean variables, and 10 or so look up variables and one "answer" variable ...
24k views

### Standard deviation of standard deviation

What is an estimator of standard deviation of standard deviation if normality of data can be assumed?
392 views

### Forecasting handbooks

In engineering, we usually have Handbooks that pretty much dictate the state of the practice. These books are usually devoid of theory and focus on the applied methodology. Is there a forecasting ...
21k views

### What is the difference between a partial likelihood, profile likelihood and marginal likelihood?

I see these terms being used and I keep getting them mixed up. Is there a simple explanation of the differences between them?
8k views

### Open Source statistical textbooks?

There have been a few questions about statistical textbooks, such as the question Free statistical textbooks. However, I am looking for textbooks that are Open Source, for example, having an Creative ...
32k views

### Is PCA followed by a rotation (such as varimax) still PCA?

I have tried to reproduce some research (using PCA) from SPSS in R. In my experience, principal() function from package psych ...
2k views

### How can one empirically demonstrate in R which cross-validation methods the AIC and BIC are equivalent to?

In a question elsewhere on this site, several answers mentioned that the AIC is equivalent to leave-one-out (LOO) cross-validation and that the BIC is equivalent to K-fold cross validation. Is there ...
632 views

### Why prediction of a predicted variable from a discriminant analysis is imperfect

I am puzzled by something I found using Linear Discriminant Analysis. Here is the problem - I first ran the Discriminant analysis using 20 or so independent variables to predict 5 segments. Among the ...
301 views

### Heuristics for optimizing ν-SVM?

Do you know any good heuristics for finding optimal value of ν in case of ν-SVM classification? In this particular problem I have a radial basis kernel, if it helps.
685 views

### Something like E-M for discriminative models?

E-M provides a way to improve the estimation of a generative model with unannotated data. Is there anything out there that works the same way for discriminative models (e.g. perceptrons)? For example,...
554 views

### E-M, is there an intuitive explanation?

The E-M procedure appears, to the uninitiated, as more or less black magic. Estimate parameters of an HMM (for example) using supervised data. Then decode untagged data, using forward-backward to '...
308 views

### To what extent can we call a Geometric Distribution a Geometric Density

In some papers, for example in "The Geometric Density with Unknown Location Parameter" by Klotz, a Geometric Distribution is called a Geometric Density. For me, this claim looks erroneous, however ...
18k views

### What are the differences between the Baum-Welch algorithm and Viterbi training?

I am currently using Viterbi training for an image segmentation problem. I wanted to know what the advantages/disadvantages are of using the Baum-Welch algorithm instead of Viterbi training.