# 2835 search results for "Twitter"

November 7, 2011
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Google slightly changed the html code it uses for hyperlinks on search pages last Thursday, thus causing one of my scripts to stop working. Thankfully, this is easily solved in R thanks to the XML package and the power and simplicity of XPath expressions: Lovely jubbly! P.S. I know that there is an API of

## Code Optimization: One R Problem, Eleven Solutions – Now Thirteen!

November 7, 2011
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Following up from my previous post “Code Optimisation: One R Problem, Ten Solutions – Now Eleven!” I figured out a twelfth solution after writing that blog post. Furthermore, half way through writing this blog post I figured out a thirteenth solution too. As a recap, the problem is taken from rwiki where the goal is to find

## Bayesian modeling using WinBUGS

November 6, 2011
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Yes, yet another Bayesian textbook: Ioannis Ntzoufras’ Bayesian modeling using WinBUGS was published in 2009 and it got an honourable mention at the 2009 PROSE Award. (Nice acronym for a book award! All the mathematics books awarded that year were actually statistics books.) Bayesian modeling using WinBUGS is rather similar to the more recent Bayesian

## The Joy of R: A Feline Guide

November 5, 2011
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Just because it’s caturday Images by Mario Pineda-Krch (CC BY-NC-SA 3.0) This is from the “Mario’s Entangled Bank” blog ( http://pineda-krch.com ) of Mario Pineda-Krch, a theoretical biologist at the University of Alberta. Filed under: cats, computing, humour, R, Sweave

## Data Referenced Journalism and the Media – Still a Long Way to Go Yet?

November 4, 2011
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Reading our local weekly press this evening (the Isle of Wight County Press), I noticed a page 5 headline declaring “Alarm over death rates at St Mary’s”, St Mary’s being the local general hospital. It seems a Department of Health report on hospital mortality rates came out earlier this week, and the Island’s hospital, it

## Confidence interval for predictions with GLMs

November 4, 2011
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Consider a (simple) Poisson regression . Given a sample where , the goal is to derive a 95% confidence interval for given , where is the prediction. Hence, we want to derive a confidence interval for the prediction, not the potential observation, i.e. the dot on the graph below > r=glm(dist~speed,data=cars,family=poisson) > P=predict(r,type="response", + newdata=data.frame(speed=seq(-1,35,by=.2))) > plot(cars,xlim=c(0,31),ylim=c(0,170)) > abline(v=30,lty=2)...

## Help: stemming and stem completion with package tm in R

November 3, 2011
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I came across a problem below when doing stemming and stem completion with package tm in R. Word “mining” was stemmed to “mine” with stemDocument(), and then completed to “miners”with stemCompletion(). However, I prefer to keep “mining” intact. For stemCompletion(), … Continue reading →

## Maximizing Omega Ratio

November 3, 2011
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$Maximizing Omega Ratio$

The Omega Ratio was introduced by Keating and Shadwick in 2002. It measures the ratio of average portfolio wins over average portfolio losses for a given target return L. Let x.i, i= 1,…,n be weights of instruments in the portfolio. We suppose that j= 1,…,T scenarios of returns with equal probabilities are available. I will

## Code Optimization: One R Problem, Ten Solutions – Now Eleven!

November 2, 2011
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Earlier this year I came across a rather interesting page about optimisation in R from rwiki. The goal was to find the most efficient code to produce strings which follow the pattern below given a single integer input n: From this we can see that the general pattern for n is: It is rather heart

## "Applications of R" contest submissions online

November 2, 2011
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Thanks to everyone for participating in the "Applications of R in Business" contest. R users submitted more than 25 entries, describing how R is used in industries including life sciences, finance, manufacturing, sentiment analysis, and even sports. Some entries are just outlines for now (competitors have until November 30 to finalize their entries), but already there are some quite...