Monthly Archives: August 2013

Classi-Compare of Raster Satellite Images – Before and After

August 13, 2013
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For my research on the effect of power outages on fertility , we study a period of extensive power rationing that lasted for almost a whole year and affected most of Latin America, but in particular, it affected Colombia. The key difficult was to determine which areas were exposed to the power-outage and the extent to

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Finding Correlations in Data with Uncertainty: Classical Solution

August 13, 2013
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Following up on my previous post as a result of an excellent suggestion from Andrej Spiess. The data are indeed very heteroscedastic! Andrej suggested that an alternative way to attack this problem would be to use weighted correlation with weights being the inverse of the measurement variance. Let’s look at the synthetic data first. This is

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When Discussing Confidence Level With Others…

August 13, 2013
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When Discussing Confidence Level With Others…

This post spawned from a discussion I had the other day. Confidence intervals are notoriously a difficult topic for those unfamiliar with statistics. I can’t really think of another statistical topic that is so widely published in newspaper articles, television, and elsewhere that so few people really understand. It’s been this way since the moment

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Genetic drift simulation

August 13, 2013
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Genetic drift simulation

While preparing for the new teaching semester I have created an implementation of NetLogo GenDrift P local in GNU R.The model works as follows. Initially a square grid having side size is randomly populated with n types of agen...

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Free R Graphics Workshop, Copenhagen, Denmark, 26th August

August 13, 2013
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Mango Solutions are pleased to announce a free R Graphics Workshop in Copenhagen on Monday 26th August (6-8pm). The workshop is open to all and any interested R users or those wishing to learn more about R.   The workshop will focus on using R to create powerful graphics, specifically covering: •             An introduction to R •             Getting data into...

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Reverse IP Address Lookups With R (From Simple To Bulk/Asynchronous)

August 12, 2013
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R lacks some of the more “utilitarian” features found in other scripting languages that were/are more geared—at least initially—towards systems administration. One of the most frustrating missing pieces for security data scientists is the lack of ability to perform basic IP address manipulations, including reverse DNS resolution (even though it has nsl() which is just

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A Stata HTML syntax highlighter in R

August 12, 2013
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So I have been having difficulty getting my Stata code to look the way I want it to look when I post it to my blog.  To alleviate this condition I have written a html encoder in R.  I don't know much about html so it is likely to be a little ...

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A beginner’s video introduction to R, from Google

August 12, 2013
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If you're an absolute beginner to the R language, this Intro to R video series from Google Developers is a great place to get started. Just download R for your system, start the playlist below, and follow along with the on-screen examples. (The video uses the MacOS X version of R, but you should be able to follow along...

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Short tales of two NCAA basketball conferences (Big 12 and West Coast) using graphs

August 12, 2013
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Short tales of two NCAA basketball conferences (Big 12 and West Coast) using graphs

Having been at the University of Kansas (Kansas Jayhawks) as a student and now working at Gonzaga University (Gonzaga Bulldogs), discussions about college basketball are inescapable. This post uses R, ggmap, ggplot2 and the shiny server to graphically ...

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Variable importance in neural networks

August 12, 2013
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Variable importance in neural networks

If you’re a regular reader of my blog you’ll know that I’ve spent some time dabbling with neural networks. As I explained here, I’ve used neural networks in my own research to develop inference into causation. Neural networks fall under two general categories that describe their intended use. Supervised neural networks (e.g., multilayer feed-forward networks)

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