Modelling with R: part 2

October 2, 2011
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Modelling with R: part 2

I apologize for the delay in the second post (just in case anybody was waiting), I had been vary involved with work the past week. I shall try to be more regular. Well, in the previous post, we successfully imported data into R and got a basic "feel" o...

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Latent class mixed models – with graphics

October 2, 2011
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Latent class mixed models – with graphics

Foreword Apologies that the output isn’t showing well as far as spacing and alignment is concerned. Am working on fixing that! Background Generally when we have a set of data, we have known groupings. Be that three different treatment groups, … Continue reading →

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Let R fly: Visualizing Export Data using R

October 2, 2011
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Let R fly: Visualizing Export Data using R

Having been using R for 5+ years, visiting www.r-bloggers.com daily, learning cool tricks from it and knowing cool UseRs from it, I finally decide to quit being an observer and start to be a contributor to this wonderful community. In this very … Continue reading →

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Overhead cost of a function call

October 1, 2011
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Overhead cost of a function call

Recently, I would like to apply unit testing method to my R program. The first thing i need to chop every few lines of the code into functions so that I can test each of them. A Question comes up to my mind: What is the overhead cost of a function call? To answer this

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Updated examples that combine Rcpp and CppBugs

October 1, 2011
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This example is very informative in illustrating how to use CppBugs module with Rcpp to conduct fast MCMC simulation in R.

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Reminder: One week til Rcpp class in San Francisco

October 1, 2011
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Just a quick note to remind everyone that the Rcpp class in San Francisco, which I am holding together with Revolution Analytics, will take place a week from today. We are happy to report that the number of registrations has met our initial target...

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Dollars and cents: How are you at estimating the total bill?

September 30, 2011
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Dollars and cents: How are you at estimating the total bill?

When estimating the cost of a bunch of purchases, a useful heuristic is rounding to the nearest dollar. (In fact, on US income tax returns, one is allowed to omit the cents). If prices were uniformly distributed, the following two heuristics would be equally accurate: * Rounding each item up or down to the nearest dollar and summing * Rounding each...

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R Graph Gallery – Donations Welcome

September 30, 2011
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R Graph Gallery – Donations Welcome

I've added a PayPal button into the graph, just in case people want to help the development of the website

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Difficult Month for One of My Best Ideas

September 30, 2011
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Difficult Month for One of My Best Ideas

THIS IS NOT INVESTMENT ADVICE.  MY IDEAS PROBABLY WILL LOSE YOU MONEY, AND I WILL NOT LET YOU KNOW WHEN I CHANGE MY MIND. Bloomberg’s article “Asian Currencies Set for Worst Month Since 1997 Crisis Caused IMF Bailouts” demonstrates why with ...

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ttrTests This is a Test Test 3:Data Snoopy

September 30, 2011
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ttrTests This is a Test Test 3:Data Snoopy

THIS IS NOT INVESTMENT ADVICE.  IT IS JUST AN EXAMPLE AND WILL LIKELY LOSE LOTS OF MONEY IF YOU PURSUE WHAT IS DISCUSSED.  READER IS RESPONSIBLE FOR THEIR OWN GAINS OR LOSSES.  IF YOU ARE AN UNLIKELY WINNER, I WOULD LOVE TO HEAR YOUR STO...

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R tutorial on visualizations/graphics

September 30, 2011
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R tutorial on visualizations/graphics

Rolf Lohaus, a Huxley postdoctoral fellow here in the EEB dept at Rice University, gave our R course a talk on basic visualizations in R this morning.Enjoy!

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R 2.13.2 released

September 30, 2011
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The R core team announced today that R 2.13.2 is now available: The byte pixies have rolled up R-2.13.2.tar.gz at 9:00 this morning. This is intended to be the final release of the 2.13 series, for the benefit of those apprehensive of putting 2.14.x into production use. This update fixes a number of minor bugs (for example, pch="." will...

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Rcpp 0.9.7

September 30, 2011
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A fresh maintenance release version 0.9.7 of Rcpp went onto CRAN and into Debian earlier today. This release contains two contributed fixes. The first, suggested by Darren Cook via the rcpp-devel mailing list, corrects how we had set up excepti...

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Microfinance Map of India – another go…

September 30, 2011
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Microfinance Map of India – another go…

I gave it another go, trying to get a map that looks a bit nicer. This time, I tried to compute something like a density or intensity in a certain area. On the previous map, this was not visible very well. I used ggplot2 and a bit of R code, together with RGoogleMaps to produce the

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Monitoring Productivity II – the Others

September 30, 2011
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Monitoring Productivity II – the Others

In previous Monitoring Productivity Experiment post I looked into the hours I spent in computer, now will look into the hours Others spend in computer, which is far more interesting :) To find things like what day people spend more time on computer, ho...

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Setting the initial view of a motion chart in R

September 30, 2011
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Setting the initial view of a motion chart in R

Following on from my article about accessing and plotting World Bank data with R I want to talk about how to change the initial view of a motion chart.Over the last couple of weeks I have been asked a view times how to do this. For instance Stephen O'G...

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Customizing your .rprofile

September 29, 2011
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I searched around to see if there was a blog post somewhere describing how to customize one’s .rprofile but was surprised to find just one outdated post. So here is quick intro on the topic. If you are a power R user, you already know about what it does. For those of you that don’t,

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Modelling with R: part 1

September 29, 2011
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Modelling with R: part 1

When I started work about 3 months ago, I didn't know much more than loading data and executing standard Econometric commands in R. But now I feel much much much more confident in using R for work, for research, for puzzles, and sometimes just for fun....

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Obama 2012 campaigning with analytics

September 29, 2011
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The campaign to re-elect US president Barack Obama is hiring -- and the RDataMining blog noticed that several of the open positions seek R skills. If you want to be a Communications Analyst, Digital Strategy Analyst, or Statistical Modeling Analyst and you know R, there may be a job opening for you. Just goes to show there's no corner...

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Googling Bayes’ pictures

September 29, 2011
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Googling Bayes’ pictures

I am writing way too many posts in a row on Google tools. I promise I will think about something else soon. I find amusing the possibility to launch a search in Google images by just dragging a picture into … Continue reading →

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A brief introduction to R for SAS and SPSS users

September 29, 2011
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If you've used SAS or SPSS and want a jump-start into the basics of the popular R language, next week's webinar, Introduction to R for SAS and SPSS Users will be of interest to you. While R, SAS and SPSS are all three software systems for data analysis and graphics, the underlying concepts in R are quite different to...

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Connect JAVA to R part 2

September 29, 2011
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To follow on from the earlier post on using R through Java, it is even easier to get jri up and running as a NetBeans module. Why is this useful? Well the platform that the NetBeans IDE is built on … Continue reading →

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Paired sample t-test in R

September 28, 2011
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Paired sample t-test in R

Let’s walk through using R and Student’s t-test to compare paired sample data. The book Statistics: The Exploration & Analysis of Data (6th edition, p505) presents the longitudinal study “Bone mass is recovered from lactation to postweaning in adolescent mothers … Continue reading →

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ttrTests This is a Test–Test 1 and Test 2

September 28, 2011
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ttrTests This is a Test–Test 1 and Test 2

Just to remind everyone, THIS IS NOT INVESTMENT ADVICE AND ANY ACTIONS TAKEN BASED ON THIS DISCUSSION WILL PROBABLY RESULT IN SIGNIFICANT LOSSES. We had fun with the ttrTests package in two previous posts ttrTests: Its Great Thesis and Incredible Poten...

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The R Graph Gallery goes social

September 28, 2011
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The R Graph Gallery goes social

The R Graph Gallery, the website from Romain François that showcases hundreds of examples of data visualization with R, has new social features. Now, when you find a graph or chart you find appealing or useful, you can "Like" it on Facebook or "+1" it on Google+. This should be a great way of highlighting the best charts and...

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Is the “Long Tail” a Useless Concept?

Is the “Long Tail” a Useless Concept?

In response to my last post, “The Long Tail of the Pareto Distribution,” Neil Gunther had the following comment:            “Unfortunately, you've fallen into the trap of using the ‘long tail’ misnomer. If you think about it, it can't possibly be the length of the tail that sets distributions like Pareto and Zipf apart; even the negative exponential and Gaussian...

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Data Science: a literature review

September 28, 2011
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Data Science: a literature review

Just what is Data Science, anyway? Here's one take: Ever since the term "Data Scientist" was coined by DJ Patil and Jeff Hammerbacker in 2009, there's been a vigorous debate on what the team actually means. More than 80% of statisticians consider themselves data scientists, but Data Science is more than just Statistics. (My own take is that Data...

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Polyploidy in sugarcane

September 28, 2011
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While reading UseR conference abstracts I came across this sentence: "Sugarcane is polypoid, i.e., has 8 to 14 copies of every chromosome, with individual alleles in varying numbers." Vau! This generates really complex genotype system. Say we have biallelic gene with alleles being A and B. In diploids the possible genotypes are AA, AB, and BB. Given the...

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Bessel integral

September 28, 2011
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Bessel integral

Pierre Pudlo and I worked this morning on a distribution related to philogenic trees and got stuck on the following Bessel integral where In is the modified Bessel function of the first kind. We could not find better than formula 6.611(4) in Gradshteyn and Ryzhik. which is for a=0… Anyone in for a closed form

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