Another Rchievement of the day

August 24, 2011
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Time for another Rchievement of the day. This is a neat little example demonstrating the power of control flow (type ?Control in R to find out more). But perhaps a not-so obvious way of using it. So what does this … Continue reading →

The problem with R? Too much new stuff!

August 23, 2011
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In a tongue-in-cheek post at the Information Management blog, Steve Miller shares his "frustration" with R: package developers keep on releasing new functionality for R that makes his own work obsolete. For example, there's now pre-packaged functionality in R for enhanced dotplots, Economist-style graphics, additive regression models and more, which all obviate the need for Steve to implement such...

expectation-propagation and ABC

August 23, 2011
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$expectation-propagation and ABC$

“It seems quite absurd to reject an EP-based approach, if the only alternative is an ABC approach based on summary statistics, which introduces a bias which seems both larger (according to our numerical examples) and more arbitrary, in the sense that in real-world applications one has little intuition and even less mathematical guidance on to

Data manipulations

August 23, 2011
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In the last Utah R Users group meeting I gave a presentation on data manipulations on R, and today I found through the plyr mailing list two commands that I was previously unaware of that should definitely be made mention of, arrage and mutate.

Z-Tests: Should we even bother?

August 23, 2011
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Should statistical teachers continue to teach z-tests?vote:  save z-test, or stop z-testLooking at textbooks, articles and general research I cannot remember the last time I saw someone use a z-test in a study. I have seen many a t-test, ANOVA, ch...

Graphically analyzing variable interactions in R

August 23, 2011
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I studied Ecology as an undergraduate, which meant I spent a lot of time gathering and analyzing field data. One of the basic tools we used to look for relationships in a large set of variables was correlation and scatterplot matrices. Each of these ...

Accelerating path-dependent loops: A quick Rcpp case study

August 23, 2011
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User BobH askedon StackOverflow about accelerating path-dependent loops. He provided a simple example in which a vector gets filled conditional on the value of the preceding element. Simple to code, but hard to vectorise.By the time I saw that q...

Anonymising data

August 23, 2011
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There are only three known jokes about statistics in the whole universe, so to complete the trilogy (see here and here for the other two), listen up: Three statisticians are on a train journey to a conference, and they get chatting to three epidemiologists who are also going to the same place. The epidemiologists are

Time Series Analysis and Mining with R

August 23, 2011
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Time series data are widely seen in analytics. Some examples are stock indexes/prices, currency exchange rates and electrocardiogram (ECG). Traditional time series analysis focuses on smoothing, decomposition and forecasting, and there are many R functions and packages available for those … Continue reading →

Random input software testing

August 23, 2011
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The usual approach to testing software is to create a specific problem and see if the software gets the correct answer.  Although this is very useful, there are problems with it: It is labor-intensive It almost totally neglects to test the code that throws errors There can be unconscious bias in the test cases created … Continue reading...

Experiences with using SAS and R in insurance and banking

August 23, 2011
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In July 2011, Hong Ooi presented an engaging talk to Melbourne R Users Group. Both David Smith from Revolutions and Eugene Dubossarsky behind the Analyst First movement have discussed the presentation. The video of the talk is now available for … Continue reading →

Experiences with using SAS and R in insurance and banking

August 23, 2011
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Hong Ooi talks about some of the more interesting projects that he has used R for in the last year. These include fitting models for mortgage loss given default, a Monte Carlo application for stress-testing loan portfolios (in combination with Excel an...

A warning on the R save format

August 23, 2011
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The save() function in the R platform for statistical computing is very convenient and I suspect many of us use it a lot. But I was recently bitten by a “feature” of the format which meant I could not recover my data. I recommend that you save data in a data format (e.g. CSV or CDF), not using...

A warning on the R save format

August 23, 2011
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The save() function in the R platform for statistical computing is very convenient and I suspect many of us use it a lot. But I was recently bitten by a “feature” of the format which meant I could not recover my data. I recommend that you save data in a data format (e.g. CSV or CDF), not using...

Maiden voyage

August 23, 2011
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WhoMe. I'm an associate professor of Statistics at Youngstown State University in Youngstown, Ohio, USA. I've been using R for about 7 years, Emacs about 3 years, git about 1 year, and Org-Mode for less than a year.WhatI want this blo...

Subjugation to the Sigmas

August 23, 2011
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No doubt you've heard about the tyranny of the 9s in reference to computer system availability. You're probably also familiar with the phrase six sigma, either in the context of manufacturing process quality control or the improvement of business processes. As we discovered in the recent Guerrilla Data Analysis Techniques class, the two concepts are related.

Popular topics at the BioStar Q&A site

August 23, 2011
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Which topics are the most popular at the BioStar bioinformatics Q&A site? One source of data is the tags used for questions. Tags are somewhat arbitrary of course, but fortunately BioStar has quite an active community, so “bad” tags are usually edited to improve them. Hint: if your question is “How to find SNPs”, then

Drawdown Visualization

August 22, 2011
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Drawdown is my favorite measure of risk.  It picks up extended autocorrelated pain often not seen in risk measures, and best illustrates frustration, panic, and loss of confidence (Drawdown Control Can Also Determine Ending Wealth).  I though...

More useR! 2011 roundups

August 22, 2011
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If you missed last week's worldwide R user conference at the University of Warwick, several attendees have posted informative roundups of the event. Check out these posts from Patrick Burns, Karl Broman, Colin Gillespie, Pairach Piboonrungroj and Richie Cotton (which features a rare, good Statistics joke). My own roundup of the conference was posted on Friday, in case you...

Webinar Wednesday Aug 24: Revolution R Enterprise, 100% R and More

August 22, 2011
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A heads-up that I'll be giving a free webinar this Wednesday, August 24. In 30 minutes, I'll give an overview of the open-source R project and the additional features of Revolution R Enterprise: R users already know why the R language is the lingua franca of statisticians today: because it's the most powerful statistical language in the world. Revolution...

Bayesian analysis: Comparing algorithms Part 1?

August 22, 2011
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$\frac{\beta^\alpha x^{\alpha-1}e^{-\beta x}}{{\Gamma(\alpha)}}$

I recently had the opportunity to engage in some Bayesian analysis at work. I was able to state the problem in terms of the lognormal distribution, and took advantage of JAGS and its integration with "R" using the R2jags package. The client was very ha...

Tenure track position in systematics at the University of Vermont

August 22, 2011
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There is an awesome position opening up for an assistant professor in systematics at the University of Vermont. Below is the announcement, and see the original post at the Distributed Ecology blog. Why is this related to R? One can do a lot of systemat...

RTextTools v1.3 Released + Rstem Now Available on CRAN

RTextTools v1.3 was released on August 21, and the package binaries are now available on CRAN. This update fixes a major bug with the stemmers, and it is highly recommended you upgrade to the latest version. Other changes include optimization of existing functions and improvements to the documentation.Additionally, Duncan Temple Lang has graciously

SIGKDD 2011 Conference — Day 1 (Graph Mining and David Blei/Topic Models)

August 22, 2011
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I have been waiting for the KDD conference to come to California, and I was ecstatic to see it held in San Diego this year. AdMeld did an awesome job displaying KDD ads on the sites that I visit, sometimes multiple times per page. That’s good targeting! Mining and Learning on Graphs Workshop 2011 I had originally planned to attend the...

R Code for Bow Tie Plots

August 22, 2011
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Earlier, I discussed the nice properties of bow tie plots for visualizing and understanding inferences from simple randomized treatment experimental designs. R code to quickly create these plots is available here. You can use the command source("htt...

Last and final on Richter’s painting

August 22, 2011
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$Last and final on Richter’s painting$

For a quick recap, Pierre and I supervised a team project at Ensae last year, on a statistical critique of the abstract painting 1024 Colours by painter Gerhard Richter. The four students, Clémence Bonniot, Anne Degrave, Guillaume Roussellet and Astrid Tricaud, did an outstanding job. Here is a selection of graphs and results they produced.

Recession forecasting II: Assessing Hussman’s Accuracy

August 22, 2011
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In my last post on recessions, I implemented John Hussman's Recession Warning Composite in R. In this post I will examine how well this index performs and discuss how we might improve it. If you would like to follow along at home, be sure to run the ...

More useless statistics

August 22, 2011
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Over at the ExploringDataBlog, Ron Pearson just wrote a post about the cases when means are useless. In fact, it’s possible to calculate a whole load of stats on your data and still not really understand it. The canonical dataset for demonstrating this (spoiler alert: if you are doing an intro to stats course, you