Example 8.42: skewness and kurtosis and more moments (oh my!)

June 27, 2011
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Example 8.42: skewness and kurtosis and more moments (oh my!)

While skewness and kurtosis are not as often calculated and reported as mean and standard deviation, they can be useful at times. Skewness is the 3rd moment around the mean, and characterizes whether the distribution is symmetric (skewness=0). Kurtos...

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A Winking Pink Elephant

June 27, 2011
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A Winking Pink Elephant

The title of chapter 5 in my Guerrilla Capacity Planning book is, "Evaluating Scalability Parameters," and underneath it you'll see this quote:"With four parameters I can fit an elephant. With five I can make his trunk wiggle." —John von NeumannIn that vein, Guerrilla alumnus Stephen O'C. pointed me at a recent blog post and paper (PDF)...

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googleVis library on use

June 26, 2011
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googleVis library on use

Data on the map While surfing around the Internet I accidentally found the googleVis library for R and especially the gvisGeoMap-function which creates a map based on country data.  In a table hockey scene we have a great World Ranking … Continu...

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NHL Statistics – Goals scored by age

June 26, 2011
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NHL Statistics – Goals scored by age

NHL Statistics, part 1 Goals scored by age Data Twirling blog gave instructions to how to get NHL statistics data from the website and I saw an opportunity to learn R and statistics with help of data I know and … Continue reading →

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RObjectTables are AWESOME

June 26, 2011
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Why isn't everyone using the RObjectTables package? This is the best thing ever! Here's the basic idea of RObjectTables: An environment is an object where you can lookup names and associate them with values. And in particular its where you look up variables used in an expression. But there's no reason you can't take any other object that associates names...

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Bayesian Fall school in La Rochelle

June 26, 2011
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Bayesian Fall school in La Rochelle

The French agronomy research institute INRA is organising a Fall school in La Rochelle, Nov. 28 – Dec. 02, on Bayesian methods, oriented towards the applications in food sciences, environmental sciences, and biology. The provisional program (in French) is ■ Initiation aux outils informatiques R et WinBUGS (TP et réalisation de projets sur ordinateur) ■

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Next Steps: Drafting the R Help Files

With RTextTools now released and the feedback rolling in, the development team is getting the ball rolling on the help documentation for the library. Currently, you cannot access help files about the library or its functions from within R. However, we do offer a draft of a quick start guide in PDF format under the Documentation section of the...

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Generalized Linear Models – Poisson Regression

June 26, 2011
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Generalized Linear Models – Poisson Regression

The Generalized Linear Model (GLM) allows us to model responses with distributions other than the Normal distribution, which is one of the assumptions underlying linear regression as used in many cases. When data is counts of events (or items) then a discrete distribution is more appropriate is usually more appropriate than approximating with a continuous

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GRIMS — General R Interface for Markov Sampling

June 25, 2011
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GRIMS — General R Interface for Markov Sampling

I have released a (very) preliminary version of my new MCMC software in R, which I’m calling GRIMS, for General R Interface for Markov Sampling. You can get it here. This software differs from other more-or-less general MCMC packages in several respects, all but one of which make it, I think, a much better tool

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Normal tail precision

June 25, 2011
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Normal tail precision

In conjunction with the normal-Laplace comparison mentioned in the most recent post about our lack of confidence in ABC model choice, we have been working on the derivation of the exact Bayes factor and I derived an easy formula for the marginal likelihood in the Laplace case that boils down to a weighted sum of

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ProjectTemplate News

June 25, 2011
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The news below was recently reported on the ProjectTemplate mailing list. For completeness, I’m also reporting it here. The first piece of ProjectTemplate news is that I won’t be the exclusive maintainer for ProjectTemplate anymore. Allen Goodman, who works at BankSimple, is now my co-maintainer and he has full commit privileges. In the next few

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R and citations

June 25, 2011
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R and citations

We’re hosting the international useR! conference at Warwick this summer, and I thought it might be interesting to try to get some data on how the use of R is growing. I decided to look at scholarly citations to R, mainly because I know where to find the relevant information. I have access to the

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R and citations by David Firth

June 25, 2011
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R and citations by David Firth

We’re hosting the international useR! conference at Warwick this summer, and I thought it might be interesting to try to get some data on how the use of R is growing. I decided to look at scholarly citations to R, mainly because I know where to f...

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Importing and displaying a Data frame with C# and R.NET

June 25, 2011
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Importing and displaying a Data frame with C# and R.NET

In this post, I give a brief and basic example of how to import a file into R and then …Continue reading »

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Kernel Density Estimates & Truncated Normals

June 24, 2011
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Kernel Density Estimates & Truncated Normals

Earlier today I read a post about truncated normals, and one plot in particular jumped out at me:By definition, the truncated normal should have zero density everywhere to the left of the truncation point, but that's not what we see in the plot. What'...

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RcppArmadillo 0.2.23

June 24, 2011
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Conrad Sanderson released version 1.99.5 of Armadillo yesterday. This provides the fifth release candidate en route to version 2.0.0. He was even kind enough to post on rcpp-devel about it too as it entails some minor API changes. His version 1.99.5 ...

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Confidence, Ending Equity, and What I Can Do as the Money Manager

June 24, 2011
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Confidence, Ending Equity, and What I Can Do as the Money Manager

I wrote this as my quarterly commentary, but compliance blocked it because they said I was implying that I am Warren Buffett or I can replicate Warren Buffett.  Anyways, I thought I should share it as a general discussion piece.  More than on...

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gretl

June 24, 2011
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In comments on a recent post, "Ben" and Tal Galili very sensibly asked if I could make R code available for the econometric analysis in my posts, in addition to EViews code. I'll be trying to do this wherever I can, given the time constraints.The important point implicit in these comments is that R is free, open-source, software, whereas...

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How to share your plots better on the web

June 24, 2011
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How to share your plots better on the web

R bloggers (including me) typically post plots online as portable network graphics (PNG). This is silly because plots generally work better as vector graphics. For years I’ve wanted to host scalable vector graphics (SVG) online, but none of the ima...

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The R Journal: June 2011

June 24, 2011
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The latest issue of the R Journal is out, and as always includes many useful articles about using R and R packages. Articles in Volume 3/1 dive into topics including creating test for R packages with test_that; dealing with times, time zones, dates and holidays with timeDate; social network analysis of mailing lists through text mining; creating choropleths and...

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Drawing heatmaps in R

June 24, 2011
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Drawing heatmaps in R

A while back, while reading chapter 4 of Using R for Introductory Statistics, I fooled around with the mtcars dataset giving mechanical and performance properties of cars from the early 70's. Let's plot this data as a hierarchically clustered heatmap. # scale data to mean=0, sd=1 and convert to matrix mtscaled <- as.matrix(scale(mtcars)) # create...

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Installing Multiple Version of R in parallel on the same machine – Mac OS X

June 24, 2011
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Installing Multiple Version of R in parallel on the same machine – Mac OS X

In a few days I'm going to attend a Bioconductor Course; I was requested to install on my MacBook (Mac OS X 10.5.8) a developer version of R (plus ad hoc Bioconductor packages). In order to keep my old R installation ((2.13) along side the ne...

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Talking The R Journal latest release

June 24, 2011
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Talking The R Journal latest release

Volume 3/1 of The R Journal has been released. It of course has articles about using R.  In addition it has a feature that I highly support.  In preparation for the UseR! Conference 2011 August 16-18 in Coventry there are two Help Desk articles on making a good technical presentation. Technical presentation Rob Hyndman writes … Continue reading...

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Multiple plots in R: lesson zero

June 24, 2011
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Multiple plots in R: lesson zero

Today, in one of my more productive days, I managed to create a sleek R script that plotted several histograms in a lattice, allowing for easy identification of the underlying trend. Although the majority of the time taken consisted of collecting the data and making various adjustments, it took a not inconsiderable amount of work to write the...

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msg <- "Hello World!"; print(msg)

June 23, 2011
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msg <- "Hello World!"; print(msg)

Introduction My mom always told me to be polite so I think I should introduce myself first. I’m a 20+ years old Finnish university student studying computer science (2nd year starting) and statistics (first year coming) and mostly interested in &...

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Table hockey and statistics, part 1

June 23, 2011
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Table hockey and statistics, part 1

Two hobbys combined I’ve been playing table hockey for little over 8 years now and since the very beginning I’ve been interested in statistics and different software we use while organising tournaments and seasons. I’ve been writing f...

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The R Journal, Volume 3/1

June 23, 2011
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The most recent issue of The R Journal was recently published.  If you're not a regular reader, you should at least check out the following three contributed articles (listed in order of appearance).Rmetrics - timeDate PackageDifferential Evoluti...

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Crashed!!

June 23, 2011
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This crashes R (sometimes): 1 2 f = function( 3 a = {x <- y <- z <- w <- t <- u <- 7} 4 ) environment() 5 6 for (i in 1:1000) { ...

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Speed up R "for" loops 50x with Rcpp

June 23, 2011
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Christian Gunning has a great example of using Rcpp to speed up a for loop in R. For his agent-based simulation, Christian needed to repeatedly call the rbinom function in a loop. (Unfortunately, you can't pass a vector to the size argument, which would have solved the problem.) Using the aaply function (from the plyr package) took about 38...

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