## Cars in Netherlands

June 2, 2013
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I am looking for a new car. So when I saw there was an update on vehicles in Statistics Netherlands I just had to go and look at the data. So, I learned the brown is getting more popular, often the number of cars from a certain construction year is lar...

June 1, 2013
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In my previous post (http://statcompute.wordpress.com/2013/05/25/test-drive-of-parallel-computing-with-r) on 05/25/2013, I’ve demonstrated the power of parallel computing with various R packages. However, in the real world, it is not straight-forward to utilize these powerful tools in our day-by-day computing tasks without carefully formulate the problem. In the example below, I am going to show how to use the

## Mapping a Revolution

June 1, 2013
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Twitter has become an important communications tool for political protests. While mass media are often censored during large-scale political protests, Social Media channels remain relatively open and can be used to tell the world what is happening and to mobilize support all over the world. From an analytic perspective tweets with geo information are

June 1, 2013
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Historical Stock Data is critical for testing your investment strategies. I illustrated all my back-test examples with getSymbols function from quantmod package. For example, following is a back-test comparison for a few portfolio allocation methods: The getSymbols function, from quantmod package, downloads historical stock prices from Yahoo Fiance. I often get questions about alternative ways

## Tweetanalytics – Interactively analyzing tweets from accounts of 5 universities

June 1, 2013
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This is an attempt at learning and interactively displaying few results using twitter data using text mining. Interactivity is implemented using RStudio's shiny server. Their documentation of demo scripts came in very handy. As a non-user of twitter, I...

## A map of the world by tweets

June 1, 2013
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With geo-tagging enabled, tweets include information on the location of the user when the tweet was sent. Miguel Rios (@miguelrios) has plotted locations of billions of tweets to create maps of the world. This is pretty amazing stuff – a world map rendered just from twitter posts! Maps are created using every tweet from 2009

## Flotsam 12: early June linkathon

June 1, 2013
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A list of interesting R/Stats quickies to keep the mind distracted: A long draft Advanced Data Analysis from an Elementary Point of View by Cosma Shalizi, in which he uses R to drive home the message. Not your average elementary point of view. Good notes by Frank Davenport on starting using R with data from

## Fylopic, an R wrapper to Phylopic

June 1, 2013
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What is PhyloPic? PhyloPic is an awesome new service - I'll let the creator, Mike Keesey, explain what it is (paraphrasing here): PhyloPic stores silhouette images of organisms, and each image is associated with taxonomic names, and stores the taxonomy of all taxa, allowing searching by taxonomic names. Anyone can submit silhouettes to PhyloPic. What is a silhouette? It's like...

## Fylopic, an R wrapper to Phylopic

June 1, 2013
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What is PhyloPic? PhyloPic is an awesome new service - I'll let the creator, Mike Keesey, explain what it is (paraphrasing here): PhyloPic stores silhouette images of organisms, and each image is associated with taxonomic names, and stores the taxonomy of all taxa, allowing searching by taxonomic names. Anyone can submit silhouettes to PhyloPic. What is a silhouette? It's like...

## Rmagic, A Handy Interface Bridging Python and R

May 31, 2013
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Rmagic (http://ipython.org/ipython-doc/dev/config/extensions/rmagic.html) is the ipython extension that utilizes rpy2 in the back-end and provides a convenient interface accessing R from ipython. Compared with the generic use of rpy2, the rmagic extension allows users to exchange objects between ipython and R in a more flexible way and to run a single R function or a block

## How logistic regression work ?

May 31, 2013
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Discussing with a non statistician colleague, it seems that the logistic regression is not intuitive; Some basics questions like : - Why don't use the linear model? - What's logistic function? - How can we compute by hand, step by step t...

## Generating Nice Looking Tree Diagrams in R

May 31, 2013
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This function generates nice looking tree diagrams (see sample) below from tree objects (generated by package tree). This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option)

## Using the rasterVis package for raster plotting (in R)

May 31, 2013
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Here is a post discussing the possibilities of the rasterVis package: http://rpubs.com/Lionel/6374Filed under: R and Stat Tagged: R, raster

## Snowfall

May 31, 2013
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Yesterday I had a short post reminding EViews users that their package (versions 7 or 8) will access all of the cores on a multi-core machine. I've been playing around with parallel processing in R on my desktop machine at work over the last few days. It's something I've been meaning to do...

## The arteries of the world, in Tweets

May 31, 2013
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What happens when you plot billions of geotagged Tweets on a map? You can see the arteries of the world. Here's Europe: According to creator Miguel Rios (Engineering Manager, Data Visualization at Twitter), the dots on this chart represent every geotagged Tweet since 2009. The color represents number of tweets in the region, and the intensity shows where people...

## Are parallel computations worth it ?

May 31, 2013
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$n$

Yesterday, Daniel Marcelino published an interesting post on his blog, untitled Parallel Processing: When does it worth ? I was asking myself the same question for a chapter I am currently writing. And I did like his approach, so I tried, on my computer to do the same. I did use three packages to run parallel R codes, >...

## Visualizing a One-Way ANOVA using D3.js

May 31, 2013
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A while ago I was playing around with the JavaScript package D3.js, and I began with this visualization—that I never really finished—of how a one-way ANOVA is calculated. I wanted to make the visualization interactive, and I did integrate some interactive elements. For instance, if you hover over a data point it will show the residual, and its value will be highlighted in...

## Regression regularization example

May 31, 2013
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Recently I needed a simple example showing when application of regularization in regression is worthwhile. Here is the code I came up with (along with basic application of parallelization of code execution). Assume you have 60 observations and 50 expla...

## accurate ABC: comments by Oliver Ratman [guest post]

May 31, 2013
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Here are comments by Olli following my post: I think we found a general means to obtain accurate ABC in the sense of matching the posterior mean or MAP exactly, and then minimising the KL distance between the true posterior and its ABC approximation subject to this condition. The construction works on an auxiliary probability

## Version control, gitbucket and SourceTree style

May 31, 2013
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Last time I wrote about version control using Subversion (and its implementation in Eclipse). I still haven’t given up on it, but since I’m using a private repository, sharing code has been a bit tedious. I was introduced to git a while ago, but somehow decided to go for Subversion. A few days ago a

## ”How to draw the line” with ggplot2

May 30, 2013
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In a recent tutorial in the eLife journal, Huang, Rattner, Liu & Nathans suggested that researchers who draw scatterplots should start providing not one but three regression lines. I quote, Plotting both regression lines gives a fuller picture of the data, and comparing their slopes provides a simple graphical assessment of the correlation coefficient. Plotting

## my 1st post for the Guardian Australia

May 30, 2013
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I’ll be contributing a piece about once a week for the Guardian Australia, under a part of the web site we’re calling The Swing. The set of graphs from my 1st effort were rendered in-line and rather low-res. Bigger, full res versions appear below; click on the in-line versions. It would be great to find

## Uncovering the Unreliable Friend Distribution

May 30, 2013
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Head down to your local hardware store and pick up a smoke detector. Pop off the cover and look inside. You’ll see a label that mentions Americium 241, a radioactive isotope. Put on your HEV suit, grab a pair of tweezers and a fine-tipped pen, and remove the 0.3 millionths of a gram of Americium.

## Scenario analysis for option strategies.

May 30, 2013
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Introduction to the project I am working on at the moment. It is more a playground for option strategies than "project" at this stage. The idea is to develop accurate scenario analysis on portfolio, which is based on a single underlying. In the past I ...

## If…then in Japan

May 30, 2013
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If Japan starts to spiral out of control, then what do they do? A spiral would be a sudden move higher in JGB rates with a simultaneous crash in the Japanese Yen. Their response would be to try to slow the positive feedback loop through external interv...

## Ryan Sheftel: "R on the Trading Desk"

May 30, 2013
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by Joseph Rickert In a post last week, I offered some first impressions about R/Finance 2013. Apparently, I was way off in estimating that 30% of the attendees were academics. The R/Finance organizers were quick to point out that percentage of academics attending the conference has been a constant 10% over the years; and this year was no different....

## Are the Current Criteria for Empirically Supported Treatments Too Lenient?

May 30, 2013
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The practice of classifying treatments as empirically supported (ESTs) has been widely debated for a long time. Recently Jessica Nasser published an article in the Journal of Contemporary Psychotherapy named “Empirically Supported Treatments and Efficacy Trials: What Steps Do We Still Need to Take?”. In the article the author raises several concerns and suggestions regarding the current use of...

## Couch, apis and all that

May 30, 2013
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It is getting easier to get data directly into R from the web. Often R packages that retrieve data from the web return useful R data structures like a data.frame or plot. This is a good thing of course to make things user friendly. However, what if you want to drill down into the data that's returned from a query...

## Are Fox News Polls Biased?

May 29, 2013
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Especially after the outcome of the mid-term election, I think there is a common contention among some groups that there is something wonky about Fox News when it comes to reporting polls relative to President Obama and the Democratic Party in general....