# All Questions

34k views

### Python as a statistics workbench

Lots of people use a main tool like Excel or another spreadsheet, SPSS, STATA, or R for their statistics needs. They might turn to some specific package for very special needs, but a lot of things can ...
29k views

### What is your favorite “data analysis” cartoon?

This is one of my favorites: One entry per answer. This is in the vein of the Stack Overflow question What’s your favorite “programmer” cartoon?. P.S. Do not hotlink the cartoon without the site's ...
13k views

### The Two Cultures: statistics vs. machine learning?

Last year, I read a blog post from Bendan O'Connor entitled "Statistics vs. Machine Learning, fight!" that discussed some of the differences between the two fields. Andrew Gelman responded to ...
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33k views

### Making sense of principal component analysis, eigenvectors & eigenvalues

In today's pattern recognition class my professor talked about PCA, eigenvectors & eigenvalues. I got the mathematics of it. If I'm asked to find eigenvalues etc. I'll do it correctly like a ...
13k views

### Detecting a given face in a database of facial images

I'm working on a little project involving the faces of twitter users via their profile pictures. A problem I've encountered is that after I filter out all but the images that are clear portrait ...
6k views

### What are common statistical sins?

I'm a grad student in psychology, and as I pursue more and more independent studies in statistics, I am increasingly amazed by the inadequacy of my formal training. Both personal and second hand ...
20k views

### Why square the difference instead of taking the absolute value in standard deviation?

In the definition of standard deviation, why do we have to square the difference from the mean to get the mean (E) and take the square root back at the end? Can't we just simply take the absolute ...
7k views

### Bayesian and frequentist reasoning in plain English

How would you describe in plain English the characteristics that distinguish Bayesian from Frequentist reasoning?
13k views

### Is there any reason to prefer the AIC or BIC over the other?

The AIC and BIC are both methods of assessing model fit penalized for the number of estimated parameters. As I understand it, BIC penalizes models more for free parameters than does AIC. Beyond a ...
18k views

### What is the difference between “likelihood” and “probability”?

The wikipedia page claims that likelihood and probability are distinct concepts. In non-technical parlance, "likelihood" is usually a synonym for "probability," but in statistical usage there is a ...
4k views

### How to annoy a statistical referee?

I recently asked a question regarding general principles around reviewing statistics in papers. What I would now like to ask, is what particularly irritates you when reviewing a paper, i.e. what's the ...
4k views

### Is $R^2$ useful or dangerous?

I was skimming through some lecture notes by Cosma Shalizi (in particular, section 2.1.1 of the second lecture), and was reminded that you can get very low $R^2$ even when you have a completely linear ...
3k views

### Explaining to laypeople why bootstrapping works

I recently used bootstrapping to estimate confidence intervals for a project. Someone who doesn't know much about statistics recently asked me to explain why bootstrapping works, i.e., why is it that ...
3k views

### Locating freely available data samples

I've been working on a new method for analyzing and parsing datasets to identify and isolate subgroups of a population without foreknowledge of any subgroup's characteristics. While the method works ...
3k views

### Why does a 95% CI not imply a 95% chance of containing the mean?

It seems that through various related questions here, there is consensus that the "95%" part of what we call a "95% confidence interval" refers to the fact that if we were to exactly replicate our ...
5k views

### Model for predicting number of Youtube views of Gangnam Style

PSY's music video "Gangnam style" is popular, after a little more than 2 months it has about 540 million viewers. I learned this from my preteen children at dinner last week and soon the discussion ...
10k views

### R vs SAS, why is SAS prefered by private companies?

I learned R but it seems that companies are much more interested in SAS experience. What are the advantages of SAS over R?
12k views

Because I find them fascinating, I'd like to hear what folks in this community find as the most interesting statistical paradox and why. This should definitely be a community wiki, though I don't ...
2k views

### What are some valuable Statistical Analysis open source projects?

What are some valuable Statistical Analysis open source projects available right now? Edit: as pointed out by Sharpie, valuable could mean helping you get things done faster or more cheaply.
1k views

### Essential data checking tests

In my job role I often work with other people's datasets, non-experts bring me clinical data and I help them to summarise it and perform statistical tests. The problem I am having is that the ...
3k views

### What is the single most influential book every statistician should read?

If you could go back in time and tell yourself to read a specific book at the beginning of your career as a statistician, which book would it be?
7k views

### Resources for learning R

I'm interested in learning R on the cheap. What's the best free resource/book/tutorial for learning R?
3k views

### What skills are required to perform large scale statistical analyses?

Many statistical jobs ask for experience with large scale data. What are the sorts of statistical and computational skills that would be need for working with large data sets. For example, how about ...
6k views

### What's wrong with XKCD's Frequentists vs. Bayesians comic?

This xkcd comic (Frequentists vs. Bayesians) makes fun of a frequentist statistician who derives an obviously wrong result. However it seems to me that his reasoning is actually correct in the ...
11k views

### What is the best introductory Bayesian statistics textbook?

Which is the best introductory textbook for Bayesian statistics? One book per answer, please.
4k views

### Which “mean” to use and when?

So we have arithmetic mean (AM), geometric mean (GM) and harmonic mean (HM). Their mathematical formulation is also well known along with their associated stereotypical examples (e.g., Harmonic mean ...
2k views

### Complete substantive examples of reproducible research using R

The Question: Are there any good examples of reproducible research using R that are freely available online? Ideal Example: Specifically, ideal examples would provide: The raw data (and ideally ...
4k views

### How to efficiently manage a statistical analysis project?

We often hear of project management and design patterns in computer science, but less frequently in statistical analysis. However, it seems that a decisive step toward designing an effective and ...
3k views

### Free statistical textbooks

Are there any free statistical textbooks available?
13k views

### Interpretation of R's lm() output

the help pages in R assume I know what those numbers mean. I don't :) I'm trying to really intuitively understand every number here. I will just post the output and comment on what I found out. There ...
2k views

### Rules of thumb for “modern” statistics

I like G van Belle's book on Statistical Rules of Thumb, and to a lesser extent Common Errors in Statistics (and How to Avoid Them) from Philipp I Good. They address common pitfalls when interpreting ...
5k views

### What book would you recommend for non-statistician scientists?

What book would you recommend for scientists who are not statisticians? Clear delivery is most appreciated. As well as the explanation of the appropriate techniques and methods for typical tasks: ...
9k views

### Is normality testing 'essentially useless'?

A former colleague once argued to me as follows: "we usually apply normality tests to the results of processes that, under the null, generate random variables that are only asymptotically or nearly ...
15k views

### What's the difference between a confidence interval and a credible interval?

Joris and Srikant's exchange here got me wondering (again) if my internal explanations for the the difference between confidence intervals and credible intervals were the correct ones. How you would ...
98k views

### What is the meaning of p values and t values in statistical tests?

After taking a statistics course and then trying to help fellow students, I noticed one subject that inspires much head-desk banging is interpreting the results of statistical hypothesis tests. It ...
3k views

### Mathematical Statistics Videos

A question previously sought recommendations for textbooks on mathematical statistics Does anyone know of any good online video lectures on mathematical statistics? The closest that I've found are: ...
2k views

### Why haven't robust (and resistant) statistics replaced classical techniques?

When solving business problems using data, it's common that at least one key assumption that under-pins classical statistics is invalid. Most of the time, no one bothers to check those assumptions so ...
13k views

### What is the difference between data mining, statistics, machine learning and AI?

What is the difference between data mining, statistics, machine learning and AI? Would it be accurate to say that they are 4 fields attempting to solve very similar problems but with different ...
3k views

### What are the 'big problems' in statistics?

Mathematics has its famous Millennium Problems (and, historically, Hilbert's 23), questions that helped to shape the direction of the field. I have little idea, though, what the Riemann Hypotheses ...
6k views

### Are large data sets inappropriate for hypothesis testing?

In a recent article of Amstat News, the authors (Mark van der Laan and Sherri Rose) stated that "We know that for large enough sample sizes, every study—including ones in which the null hypothesis of ...
18k views

### Good GUI for R suitable for a beginner wanting to learn programming in R?

Is there any GUI for R that makes it easier for a beginner to start learning and programming in that language?
4k views

### What is the best way to identify outliers in multivariate data?

Suppose I have a large set of multivariate data with at least three variables. How can I find the outliers? Pairwise scatterplots won't work as it is possible for an outlier to exist in 3 dimensions ...
24k views

### Statistics Jokes

Well we've got favourite statistics quotes. What about statistics jokes? So, what's your favourite statistics joke?
14k views

### Difference between logit and probit models

Can anybody please tell me the difference between the logit and the probit model? I'm more interested here in knowing when to use logistic regression, and when to use probit. If there's any literature ...
2k views

### Does causation imply correlation?

Correlation does not imply causation, as there could be many explanations for the correlation. But does causation imply correlation? Intuitively, I would think that the presence of causation means ...
2k views

### What is intuition behind beta distribution?

Disclaimer: I'm not statistician but rather software engineer. Most of my knowledge in statistics comes from self-education, thus I still have many gaps in understanding concepts that may seem trivial ...
1k views

### What is a good resource on table design?

I've seen various theoretical treatments of graphics, such as the Grammar of Graphics. But I have seen nothing equivalent with regards to tables. Over the while I have developed an informal model of ...