Initializing the Holt-Winters method

November 29, 2010 | Rob J Hyndman

The Holt-Winters method is a popular and effective approach to forecasting seasonal time series. But different implementations will give different forecasts, depending on how the method is initialized and how the smoothing parameters are selected. In this post I will discuss various initialization methods. Suppose the time series is denoted ... [Read more...]

CrossValidated launched!

November 4, 2010 | Rob J Hyndman

The CrossValidated Q&A site is now out of beta and the new design and site name is live. New design The new design looks great, thanks to Jin Yang, our designer-in-residence. Note the normal density icon for accepted answers and the site icon depicting a 5-fold cross-validation (light green ... [Read more...]

Findings increasingly novel, scientists say…

October 29, 2010 | nsaunders

…was the tongue-in-cheek title of an image that I posted to Twitpic this week. It shows the usage of the word “novel” in PubMed article titles over time. As someone correctly pointed out at FriendFeed, it needs to be corrected for total publications per year. It was inspired by a ...
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Different results from different software

October 26, 2010 | Rob J Hyndman

I’ve had a few questions on this topic lately. Here is an email received today: I use Eviews to estimate time series, but I have been checking out R recently, and your Forecast package. I cannot understand why 2 similar equations in Eviews and R are giving different estimated output. ... [Read more...]

How fast is JAGS?

October 6, 2010 | jackman

From Martyn Plummer, on the JAGS news blog. Key graph below, showing a few outlying cases in which JAGS is substantially slower than OpenBUGS, but generally, JAGS performs quite favorably. Key point from Martyn: Incidentally, these figures are for JAGS with the glm module loaded. The glm module is not ...
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A texteditor for R

September 29, 2010 | Rob J Hyndman

I’ve been using RWinEdt for the last few years for all my R coding. But it no longer works with WinEdt 6.0 and no update has been forthcoming. Consequently, I’ve been looking around for something similar to take its place. This question has been asked before on StackOverflow and ...
[Read more...]

What should we call the stats Q&A site?

September 18, 2010 | Rob J Hyndman

The Q&A site at has been steaming ahead with loads of good questions and answers. We are currently trying to select a name and not many people have voted. Although we have more than 1300 users of the site, less than 40 people have currently voted on the ...
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A brief introduction to “apply” in R

August 19, 2010 | nsaunders

At any R Q&A site, you’ll frequently see an exchange like this one: Q: How can I use a loop to [...insert task here...] ? A: Don’t. Use one of the apply functions. So, what are these wondrous apply functions and how do they work? I think the ... [Read more...]

Statistical Analysis StackExchange site now available

July 26, 2010 | Rob J Hyndman

The Q&A site for statistical analysis, data mining, data visualization, and everything else to do with data analysis has finally been launched. Please head over to and start asking and answering questions. Also, spread the word to everyone else who may be interested — work colleagues, students, ...
[Read more...]

More StackExchange sites

July 16, 2010 | Rob J Hyndman

The StackExchange site on Statistical Analysis is about to go into private beta testing. This is your last chance to commit if you want to be part of the private beta testing. Don’t worry if you miss out — it will only be a week before it is then open ...
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Stack exchange for statistical analysis needs you!

June 17, 2010 | Rob J Hyndman

The proposal to create a StackExchange site for statistical analysis is steadily moving forward. We have now completed the scoping stage which involved finding enough people willing to express an interest in the idea, and voting on some example questions to define what is allowed and what is not allowed ... [Read more...]

Beware of rogue header files (Bioconductor installation)

May 11, 2010 | nsaunders

Just a short note concerning a “gotcha”. As I have many times before, I opened an R console on my newly-upgraded (to lucid 10.04) Ubuntu machine, typed source(“”) and began a Bioconductor install with biocLite(). Only this time, I saw this: Error in dyn.load(file, ... [Read more...]

Stata Fail

March 10, 2010 | jackman

From a recent mailing from Stata (highlighting by me): Funnily enough, there is a Daniel Rubin, a bio-informatics person here at Stanford. [Read more...]

principal components and image reconstruction

March 9, 2010 | jackman

Jeff Lewis at UCLA told me he teaches principal components with an image reconstruction example. This got me inspired to try it myself. A snapshot appears below, showing how the image quality improves quickly with a relatively small number of principal components. A full, Sweaved write up is here, making ... [Read more...]

sequential ideal point estimates

January 9, 2010 | jackman

Out of curiosity, I produced a “sequential” set of ideal point estimate for the (current) 111th U.S. Senate, plotting the results in the graph attached below (click on the thumbnail); as is conventional, red is Republican and blue is Democratic. The analysis uses all 373 non-unanimous roll calls in the 111...
[Read more...]

A brief survey of R web interfaces

November 29, 2009 | nsaunders

I’m looking at ways to provide access to R via a web application. First rule: see what’s available first, before you reinvent the wheel. It’s not pretty. From the R Web Interfaces FAQ: Software Brief notes Rweb Page last updated 1999. Of the 3 example links on the page ... [Read more...]
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