January 2010

Typos in Chapter 4

January 9, 2010 | xi'an

Chapter 4 of “Introducing Monte Carlo Methods with R” has four typos (so far) in the exercises: – In Exercise 4.5, the should not be in bold fonts (!) – In Exercise 4.9, I commented too many lines when revising and thus the variance terms vanished. It should read – In Exercise 4.13, following the removal of [...]
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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...
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Killing Yourself: An Addendum

January 9, 2010 | John Myles White

In further support of the claim that a lot of deaths are partly self-induced, here’s a fascinating piece by Wired on the extraordinary rise in the percent of deaths among the young caused by their own poor decisions. It’s remarkable that, for the young, modern science has already ... [Read more...]

Because it’s Friday: Gravity Wells

January 8, 2010 | David Smith

It's a little strange to see a web comic come up with such interesting visualizations, but xkcd has followed up on their movie timelines charts with this illustration of the gravitational attraction of the various bodies in the solar system. The gravitational force at the surface of the planet or ... [Read more...]

External pointers with Rcpp

January 8, 2010 | romain francois

pre{ border: 1px solid black ; font-size: x-small; } One of the new features of Rcpp is the XPtr class template, which lets you treat an R external pointer as a regular pointer. For more information on external pointers, see Writing R extensions... [Read more...]

R Tutorial Series: ANOVA Tables

January 8, 2010 | John M. Quick

The commonly applied analysis of variance procedure, or ANOVA, is a breeze to conduct in R. This tutorial will explore how R can be used to perform ANOVA to analyze a single regression model and to compare multiple models.Tutorial FilesBefore we begin,...
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Codecogs – Open-Source library of numerical components

January 8, 2010 | Ralph

The Codecogs website provides an Open-source library of functions for numerical analysis. One interesting component available on the website is the LaTeX equation editor which can be used to create graphics files of equations to include on webpages. The webpage describe this component as a A web-based LaTeX equation editor ... [Read more...]

Typos in Chapter 3

January 7, 2010 | xi'an

Here are two more typos in the exercises of Chapter 3 of “Introducing Monte Carlo Methods with R”. – due to the (later) inclusion of an extra-exercise in the book, the “above exercise” in Exercise 3.5 actually means Exercise 3.3. – in Exercise 3.11, question c, a line got commented by mistake in the LaTeX file ...
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R’s exponential package growth, ctd.

January 7, 2010 | David Smith

Reader SK has collected the most recent data on R's package growth, through the latest 2.10 release. The three most recent releases fall slightly below the exponential growth line, which isn't altogether surprising (that's a lot of growth to sustain!). Another interesting thing to look at would be the combined rate ... [Read more...]

Survey question biases and crowdsourcing

January 7, 2010 | David Smith

It's common knowledge that the way you ask a question in a survey can bias the results you get. (It's been a staple of political pollsters since the dawn of time.) But Aaron Shaw from Dolores Labs has used an interesting technique to demonstrate that bias: crowdsourcing. He asked the ... [Read more...]

subsetting a matrix/array in R

January 7, 2010 | jackman

From the R-devel svn log. Nice addition… r50896 | falcon | 2010-01-05 12:05:31 -0800 (Tue, 05 Jan 2010) | 7 lines Changed paths: M /trunk/NEWS M /trunk/src/include/Defn.h M /trunk/src/library/base/man/Extract.Rd M /trunk/src/main/subassign.c M /trunk/src/main/subscript.c M /trunk/src/main/... [Read more...]

3d scatter plot using R

January 6, 2010 | er

The other day I saw a three dimensional scatterplot in Montgomery's Regression book. I wanted to redraw the graph using the provided data. A simple google search revealed that there is a package called scatterplot3d. The scatterplot3d() can be used to draw a 3-dimensional scatter plot. Here is ... [Read more...]

Programming a custom Backtest Profile in R

January 6, 2010 | Milk Trader

One of the many issues with systems trading is trying to make sense of the vast amounts of data you accumulate with the backtest of a system. Historical backtesting is the first step in testing your trading idea. If it is a trading idea that ought to w...
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