2765 search results for "GIS"

Word Clouds in R

September 13, 2012
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Word Clouds in R

Thanks to the wordcloud package, it's super easy to make a word cloud or tag cloud in R.In this case, the words have been counted already. If you are starting with plain text, you can use the text mining package tm to obtain the counts. Other blog...

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Second Milano R net meeting

September 11, 2012
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Second Milano R net meeting

September 27, 2012 - 18:00 - 21:00 Fiori Oscuri Bistrot & Bar (www.fiorioscuri.it) Via Fiori Oscuri, 3 - Milano (Zona Brera) Continue reading →

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Item Response Theory: Developing Your Intuition

September 10, 2012
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Item Response Theory: Developing Your Intuition

Suppose that you accepted my argument from the last two posts on halo effects and bifactor models.  As you might recall, I argued that when respondents complete rating scales, they predominating rely on their generalized impression with a more minor role played by the specific features that the ratings were written to measure.  Consequently, we...

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Violence along Mexico’s Southern Border and Central America

September 7, 2012
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Violence along Mexico’s Southern Border and Central America

Rates for Panama and Nicaragua are from 2009, all other countries 2010. Municipalities which are part of a metro area in Mexico are shown with the metro area homicide rate.Visit the interactive map of homicides Having just posted on violence along Mexico's northern border, I figured it's time to...

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Big Issue with System Backtests

September 7, 2012
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Big Issue with System Backtests

Almost always, when I see a system backtested, the backtest assumes a static portfolio with no contributions or withdrawals.  This assumption only covers an extremely limited subset of my clients.  Cash flows in and out of a portfolio or syst...

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More on fixed and random effects: Plotting and interpreting

September 7, 2012
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More on fixed and random effects: Plotting and interpreting

In a recent post I showed how plotting model fits can help to interpret higher-order polynomial terms. The key comparison there was between a model that did and did not have the higher order fixed effect terms. If you're going to use this strategy, you need to...

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Coming up: Two weeks of awesome guest bloggers

September 7, 2012
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I'm heading out on vacation to my Australian homeland for the next two weeks, but fear not reader friends: we have an awesome lineup of guest bloggers to fill in while I'm away. I don't want to ruin the surprise, but you'll be seeing posts from: experts in data visualization about how they use R; members of the R...

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The future of Artificial Intelligence – as imagined in 1989

September 6, 2012
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The future of Artificial Intelligence – as imagined in 1989

This image comes from the cover of Preliminary Papers of the Second International Workshop on Artificial Intelligence and Statistics (1989). Someone abandoned it in the lobby of my building at school. Whatever for, I’ll never know. I just love the idea of machine learning/AI/Statistics evoking a robot hand drawing a best fit line through some

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BaselR meetup

September 6, 2012
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Mango Solutions host BaselR, a free, open and informal R user group for those using or interested in using R. There will be a few short R related presentations and an opportunity to meet and chat with other R users over a drink. Date: Thursday 13th September at 6.30pm. Venue : transBarent, Viaduktstrasse 3, Basel (by the train station)...

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Comparing Stan to JAGS for Bayesian Inference (Part 1?)

September 5, 2012
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Comparing Stan to JAGS for Bayesian Inference (Part 1?)

Stan is a new, open source, Bayesian inference tool. Stan is based on the the No-U-Turn sampler, a variant of Hamiltonian Monte Carlo. In order to compare Stan with JAGS, a gibbs sampler approach to Bayesian inference, I used the classic WinBUGS rats example. The rats example uses a hierarchical model to look at...

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