September 2012

Item Response Theory: Developing Your Intuition

September 10, 2012 | Joel Cadwell

Suppose that you accepted my argument from the last two posts on halo effects and bifactor models.  As you might recall, I argued that when respondents complete rating scales, they predominating rely on their generalized impression with a more minor role played by the specific features that the ratings were ... [Read more...]

Example 10.1: Read a file byte by byte

September 10, 2012 | Ken Kleinman

More and more makers of electronic devices use standard storage media to record data. Sometimes this is central to the device's function, as in a camera, so that the data must be easy to recover. Other times, it's effectively incidental, and the device maker may not provide easy access to ... [Read more...]

Population health management with RevoScaleR

September 10, 2012 | David Smith

This guest post is by Douglas McNair MD PhD, Engineering Fellow & President, Cerner Math Inc. -- ed. RevoScaleR scaling big-data modeling performance for real-time health data analysis at Cerner The size of data sets is increasing much more rapidly than the speed of cores, of RAM, and of disk drives. ... [Read more...]

INLA functions (continued)

September 10, 2012 | Gianluca Baio

I have polished up one of the two functions I've thought of implementing for INLA and it's now available in the development version of the R package. So if you've got INLA installed in your R version (see how you can do it here, if you don't), you... [Read more...]

Progress bars in R using winProgressBar

September 10, 2012 | bryan

Using progress bars in R scripts can provide valuable timing feedback during development and additional polish to final products. winProgressBar and setWinProgressBar are the primary functions for creating progress bars in R. Progress bars, and progress indicators in general, are relatively uncommon in R programming. This makes sense, as they ... [Read more...]

Not fooled by randomness

September 10, 2012 | Pat

The paper is “Not Fooled by Randomness: Using Random Portfolios to Analyze Investment Funds” by Roberto Stein.  Here is an explanation of the idea of random portfolios. Favorite sentence The real question here is whether we’re actually measuring skill, or these are still measures of performance, so influenced by ... [Read more...]

R Package Vignettes with Markdown

September 10, 2012 | Yihui Xie

What is the best resource to learn an R package? Many R users know the almighty question mark ? in R. For example, type ?lm and you will see the documentation of the function lm. If you know nothing about a package, you can take a look at the HTML help... [Read more...]

Core minus one!

September 9, 2012 | xi'an

Jean-Michel Marin visited me in Paris last week and, besides taking part in Pierre’s PhD defence, we made enough progress to close two more chapters of the new edition of Bayesian Core (soon to be Bayesian Essentials with R!) This follows the good work session we had in Carnon ... [Read more...]

Football predictions display

September 9, 2012 | Wingfeet

Having looked at the football data earlier, I wanted to look at predictions for new games. This consists of two parts, getting a predictive model, predicting and displaying the predictions. I decided to do this backwards, first to make the displays. Th...
[Read more...]

RInside 0.2.8

September 8, 2012 | Thinking inside the box

This morning version 0.2.8 of RInside arrived on the CRAN sites. RInside provides a set of convenience classes which facilitate embedding of R inside of C++ applications and programs, using the classes and functions provided by the Rcpp R and C++ in... [Read more...]

Big Issue with System Backtests

September 7, 2012 | klr

Almost always, when I see a system backtested, the backtest assumes a static portfolio with no contributions or withdrawals.  This assumption only covers an extremely limited subset of my clients.  Cash flows in and out of a portfolio or syst...
[Read more...]

Simulation metamodeling with GNU R

September 7, 2012 | Bogumił Kamiński

I am one of the organizers of ESSA2013 conference that will take place in September 2013 in Warsaw, Poland. The conference scope is social simulation and in particular methods of statistical analysis of simulation output (metamodeling). As we have just issued Call for Papers for the conference so I decided to ... [Read more...]
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