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Smaller or greater? – episode II

May 20, 2011
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Smaller or greater? – episode II

In a previous post I introduced the following game: Suppose you play the following game: Someone holds a set of cards with the numbers {1,2,…,N} in random order, opens up the first card and asks if the next card is greater or smaller. Every time you predict correctly, you get one point, while every wrong

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Great circles, raster, sp and lattice

Great circles, raster, sp and lattice

Recently I found a post at FlowingData with a detailed tutorial to map connections with great circles with R. The tutorial of FlowingData is excellent, but I feel more comfortable with the sp classes and methods, and with the lattice and latticeExtra packages. Besides, I want to use the free spatial data available from the

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Syntax highlighting of R code at WordPress.com

May 20, 2011
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Syntax highlighting of R code at WordPress.com

If your WordPress blog is hosted at WordPress.com (like this one), you may know that source code in posts is formatted and highlighted using a shortcode, as explained here. Until recently, R was not on the list of supported languages (neither was Perl), but I noticed today that both of them are now supported. This

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Friday fun with: Google Trends

May 19, 2011
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Friday fun with: Google Trends

Some years ago, Google discovered that when people are concerned about influenza, they search for flu-related information and that to some extent, search traffic is an indicator of flu activity. Google Flu Trends was born. Illness is sweeping through our department this week and I have succumbed. It’s not flu but at one point, I

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Stata-like Marginal Effects for Logit and Probit Models in R [2]

May 18, 2011
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Stata-like Marginal Effects for Logit and Probit Models in R [2]

My thanks to those who emailed comments and suggestions for my ‘mfx’ function, I’m happy that I could fill a void for some people. I also received a request/suggestion from Tony Cookson, along with a helpful fix for a bug in the code, to include an option that would allow the user to specify values

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Stata-like Marginal Effects for Logit and Probit Models in R

May 17, 2011
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Stata-like Marginal Effects for Logit and Probit Models in R

Although this blog’s primary focus is time series, one feature I missed from Stata was the simple marginal effects command, ‘mfx compute’, for cross-sectional work, and I could not find an adequate replacement in R. To bridge this gap, I’ve written a (rather messy) R function to produce marginal effects readout for logit and probit

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A survey of the [60′s] Monte Carlo methods [2]

May 17, 2011
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A survey of the [60′s] Monte Carlo methods [2]

The 24 questions asked by John Halton in the conclusion of his 1970 survey are Can we obtain a theory of convergence for random variables taking values in Fréchet spaces? Can the study of Monte Carlo estimates in separable Fréchet spaces give a theory of global approximation? When sampling functions, what constitutes a representative sample

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How to do a quantitative literature review in R

May 17, 2011
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How to do a quantitative literature review in R

In the early stages of a literature review, you may have hundreds of papers and not know how to even begin sorting through them. In this post, I show you how to perform a two-stage clustering analysis with R so that you can identify the main groups within your data, based on key attributes of each paper.

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AIB Stock Price, EGARCH-M, and rgarch

May 17, 2011
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AIB Stock Price, EGARCH-M, and rgarch

This post examines conditional heteroskedasticity models in the context of daily stock price data for Allied Irish Banks (AIB), specifically how to test for conditional heteroskedasticity in a series, how to approach model specification and estimation when time-varying volatility is present, and how to forecast with these models; all of this is done in R,

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In case you missed it: April Roundup

May 17, 2011
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In case you missed them, here are some articles from April of particular interest to R users. The Heritage Health Prize, a competition to build predictive models for hospitalization with USD$3.2M in prizes, is open. The Inside-R.org community site now provides the ability to search and view the help files for CRAN packages. Revolution R Enterprise 4.3 released: R...

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