September 2013

Regression on variables, or on categories?

September 30, 2013 | arthur charpentier

I admit it, the title sounds weird. The problem I want to address this evening is related to the use of the stepwise procedure on a regression model, and to discuss the use of categorical variables (and possible misinterpreations). Consider the following dataset __ db = read.table("http://freakonometrics.free.fr/... [Read more...]

Which is the best "Flyover" state?

September 30, 2013 | David Smith

If you were to hop into your personal aircraft, and plotted a straight line course taking off in one state and landing in the SAME state, how many other states might you fly over? On other words, what's the best state for "flyovers" of other states? Todd Schnieder from the ... [Read more...]

How heavy is the Siberut macaque? A Bayesian phylogenetic approach

September 30, 2013 | Maxwell B. Joseph

Among-species comparisons can include phylogenetic information to account for non-independence arising from shared evolutionary history. Often, phylogenetic topologies and branch lengths are not known exactly, but are estimated with uncertainty. This uncertainty can be accounted for using methods recently described in a neat paper called Bayesian models for comparative analysis ... [Read more...]

An R function to download shapefiles

September 30, 2013 | Jeffrey Hollister

This post is a follow up from my latest Things I Forget post on reading in shapefiles.  That post assumed that you already had access to all the relevant files (e.g. .shp, .shx, .prj, .dbf, etc.).  A task that I routinely need to do is locate shapefiles on a ... [Read more...]

A Bayesian Twist on Tukey’s Flogs

September 30, 2013 | Rasmus Bååth

In the last post I described flogs, a useful transform on proportions data introduced by John Tukey in his Exploratory Data Analysis. Flogging a proportion (such as, two out of three computers were Macs) consisted of two steps: first we “started” the proportion by adding 1/6 to each of the counts ... [Read more...]

ROC curves and classification

September 30, 2013 | arthur charpentier

To get back to a question asked after the last course (still on non-life insurance), I will spend some time to discuss ROC curve construction, and interpretation. Consider the dataset we’ve been using last week, __ db = read.table("http://freakonometrics.free.fr/db.txt",header=TRUE,sep=";") __ attach(db) ... [Read more...]

RcppArmadillo 0.3.920.1

September 30, 2013 | Thinking inside the box

Along with the Rcpp 0.10.5 release yesterday, a new minor release 0.3.920.1 of RcppArmadillo came out. It is based on Conrad's Armadillo 3.920.0 plus a minor fix, and uses some of the new Rcpp features. Both package is now on CRAN and also in Debian.... [Read more...]

New version of lme4

September 30, 2013 | Dan Mirman

If you haven't realized it yet, a new version of lme4 (version 1.0-4) was released recently (Sept. 21). For an end-user like me, there were not many changes, but there were a few:No more using the @ operator. After a very helpful email exchange with Be... [Read more...]

Testing R Packages

September 29, 2013 | Yihui Xie

This guy th3james claimed Testing Code Is Simple, and I agree. In the R world, this is not anything new. As far as I can see, there are three schools of R users with different testing techniques: tests are put under package/tests/, and a foo-test.Rout.save from ... [Read more...]

Measuring Randomness in Capital Markets

September 29, 2013 | Kelly Littlepage

What is Random? As previously discussed, there’s no universal measure of randomness. Randomness implies the lack of pattern and the inability to predict future outcomes. However, The lack of an obvious model doesn’t imply randomness anymore than a curve fit one implies order. So what actually constitutes randomness, ... [Read more...]

Rcpp 0.10.5

September 29, 2013 | Thinking inside the box

A new version of Rcpp is now on the CRAN network for GNU R; binaries for Debian have been uploaded as well. Once more, this release brings a large number of exciting changes to Rcpp. Some concern usability, some bring new features, some increase pe... [Read more...]

Classification with O-PLS-DA

September 29, 2013 | dgrapov

Partial least squares (PLS) is a versatile algorithm which can be used to predict either continuous or discrete/categorical variables. Classification with PLS is termed PLS-DA, where the DA stands for discriminant analysis.  The PLS-DA algorithm has many favorable properties for dealing with multivariate data; one of the most important ... [Read more...]

Nice tutorials to discover R

September 28, 2013 | arthur charpentier

A series of tutorials, in R, by Anthony Damico. As claimed on http://twotorials.com/, “how to do stuff in r. two minutes or less, for those of us who prefer to learn by watching and listening“. So far, 000 what is r? the lingua statistica, s’il vous plaît 001 ... [Read more...]

Visualizing “ObamaCare-related” Job Cuts

September 28, 2013 | hrbrmstr

I was reviewing RSS feeds when I came across this story about “ObamaCare Employer Mandate: A List Of Cuts To Work Hours, Jobs” over on Investors.com. Efficacy of the law notwithstanding, I thought it might be interesting to visualize the data since the folks over at Investors.com provided ...
[Read more...]

Making of elliplot package

September 28, 2013 | tomizono

The elliplot package is my first package for R.  So I want to write down details of making that, both for myself and for people following. original source The ellipseplot … Continue reading → [Read more...]

Le Monde puzzle [#835]

September 28, 2013 | xi'an

The current puzzle is apparently suffering from combinatoric complexity : N persons (with 20≤N≤23) are sitting around a round table and everyone has a green or red token. Both colours are represented. First, each player with a red token take the token of the player immediately to her or his left. ...
[Read more...]

Conditional Formatting Tables using R

September 28, 2013 | Educate-R - R

One thing that I had the opportunity to develop while working last year at Saint Paul Public Schools was figuring out a quick, easy, and painless way to do interactive report generation. When I arrived in the REA department at Saint Paul Public Schools, the report generation process was roughly ... [Read more...]

elliplot 1.1.0 package released

September 27, 2013 | tomizono

I released R package elliplot version 1.1.0. This package contains ellipseplot and midpoints. It is to visualize a correlation between 2 sets of independent observation with common factors.  Details are … Continue reading → [Read more...]
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