Monthly Archives: February 2010

One-way Analysis of Variance (ANOVA)

February 3, 2010
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One-way Analysis of Variance (ANOVA)

Analysis of Variance (ANOVA) is a commonly used statistical technique for investigating data by comparing the means of subsets of the data. The base case is the one-way ANOVA which is an extension of two-sample t test for independent groups covering situations where there are more than two groups being compared. In one-way ANOVA the data

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Advanced graphics in R

February 3, 2010
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A lot of attention recently has gone to the more modern (and, dare I say, sexier) graphics systems in R, ggplot2 and lattice. But there's a lot of power in the base graphics system built into core R, especially when you want control over every aspect of how the graph is laid out. Ryan Rosario has put together some...

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Web Development with R – an HD video tutorial of Jeroen Ooms talk

February 3, 2010
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Here is a HD version of a video tutorial on web development with R, a lecture that was given by Jeroen Ooms (the guy who made A web application for R’s ggplot2). This talk was given at the Bay Area UseR Group meeting on R-Powered Web Apps.You can also view the slides for his talk and view (great) examples for: stockplot, lme4, and gpplot2. Thanks...

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Predicting the Locations of ‘Emergency’ Ushahidi Reports in Port-au-Prince, and Implications for Crowdsourcing

February 2, 2010
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Predicting the Locations of ‘Emergency’ Ushahidi Reports in Port-au-Prince, and Implications for Crowdsourcing

Recently, Patrick Meier, PhD candidate at Tufts University and member of the Ushahidi Advisory Board, provided me with a dataset containing the first 72 hours of reports registered with Ushahidi in Port-au-Prince after the January 12th earthquake. First, a huge thank you to Patrick for providing me with this data and the opportunity to analyze

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In case you missed it: January roundup

February 2, 2010
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In case you missed them, here are some articles from last month of particular interest to R users. This post linked to slides and video from a 30-minute "Introduction to R" talk I gave on January 28, with links to many useful R resources. This post brought news that R's creators Robert Gentleman and Ross Ihaka have jointly won...

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Survey: Share your thoughts about predictive models with Aberdeen Group

February 2, 2010
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Analyst firm Aberdeen Group is conducting research into the use of predictive models in business with a 10-minute survey. It's focused mainly on businesses that are using (or plan to use) predictive models to forecast aspects of their business and the systems they have in place (or plan to put in place) to do so. If you're using predictive...

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The Power to … What did you say?

February 2, 2010
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The Power to … What did you say?

It is just about a year ago (exactly January 6th, 2009) that a New York Times article on R did fuel the dispute on what statistical analysis tool is “the best”. One of the highlight of the article was a quote from SAS’ Anne H. Milley: “I think it addresses a niche market for high-end

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Ensemble Prediction

February 2, 2010
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Ensemble Prediction

Weather is unpredictable. Small differences in initial conditions can develop into big differences in the pattern of circulation, in the timing and location of cyclones, rainfall etc. This is true no matter how good the initial observing system is. The approach taken by organisations such as ECMWF or NCEP is to re-run numerical forecast models

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Practical Implementation of Neural Network based Time Series (Stock) Prediction – PART 3

February 1, 2010
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Practical Implementation of Neural Network based Time Series (Stock) Prediction – PART 3

Ok, now that we have seen how well the perfect sine wave signal was learned, let's turn it up a notch and see how well the complex sine wave was learned.Fig 1. Summary of Actual Vs. Predicted out of sample complex sine waveformUh Oh. What happened, the...

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InfoWorld: SAS and SPSS rise to R opportunity

February 1, 2010
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At InfoWorld's "Open Source" blog Salvio Rodrigues found R co-inventor Robert Gentleman's appointment to the REvolution Computing board "a great impetus for me to look at R again". He notes that both SAS and SPSS have recognized the opportunity presented by R: I suspect that SPSS and SAS made their individual decisions based on three factors. First, they likely...

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