2442 search results for "gis"

Visualizing Sampling Distributions

September 25, 2011
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Visualizing Sampling Distributions

Teacher: “How variable is your estimate of the mean?” Student: “Uhhh, it’s not. I took a sample and calculated the sample mean. I only have one number.” Teacher: “Yes, but what is the standard deviation of sample means?” Student: “What do you mean means, I only have the one friggin number.” Statisticians have a habit

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Are new SEC rules enough to prevent another Flash Crash?

September 22, 2011
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Are new SEC rules enough to prevent another Flash Crash?

At 2:42PM on March 10 2010, without warning, the Dow Jones Industrial Index plunged more than 1000 points in just 5 minutes. It remains the biggest one-day decline in this stock market index in history. On an intra-day basis, anyway: by the end of the day, the market had regained 600 points of the drop. At the time, the...

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Recession forecasting III: A Better Naive Forecast

September 20, 2011
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Recession forecasting III: A Better Naive Forecast

In Recession Forecasting Part II, I compared the accuracy of Hussman's recession forecasts to the accuracy of a naive forecast that assumed the current state of the recession variable would continue next month.An anonymous comment...

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rgdal + raster + RCurl = My next package

September 18, 2011
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rgdal + raster + RCurl = My next package

This package has been a long time in the making.  In the end it’s more of a data package than a functional package, but pulling all the pieces together required me to learn some really cool packages: raster ( which I already knew ) rgdal and RCurl.  I’ll provide a littel bit of an overview

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Implementation of the CDC Growth Charts in R

September 17, 2011
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I implemented in R a function to re-create the CDC Growth Chart, according to the data provided by the CDC.In order to use this function, you need to download the .rar file available at this megaupload link.Mirror: mediafire link.Then unrar the file, a...

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Backtesting Part 2: Splits, Dividends, Trading Costs and Log Plots

September 16, 2011
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Backtesting Part 2: Splits, Dividends, Trading Costs and Log Plots

Note: This post is NOT financial advice!  This is just a fun way to explore some of the capabilities R has for importing and manipulating data.  In my last post, I demonstrated how to backtest a simple momentum-based stock trading strategy ...

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Soil Series Query for SoilWeb

September 16, 2011
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Soil Series Query for SoilWeb

A map depicting the spatial distribution of a given soil series can be very useful when working on a new soil survey, updating an old one, or searching for specific soil characteristics. We have recently added a soil series query facility to SoilWeb, w...

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Simulation studies in R – Using all cores and other tips

September 16, 2011
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After working more seriously with simulations I noticed some updates were necessary to my previous setup. Most notably are the following three: It is very handy to explicitly call the different scenarios instead of using nested loops Storing intermediate results in single files obliviates the need to rerun an almost finished but crashed analysis and

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Correlations among US Stocks: Is it really time to fire your adviser?

September 15, 2011
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Correlations among US Stocks: Is it really time to fire your adviser?

Note: This post is NOT financial advice!  This is just a fun way to explore some of the capabilities R has for importing and manipulating data.The Financial Times says it's time to "Fire your Adviser" because correlations among US stocks ar...

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Revolution Analytics Fall Webinar Series

September 14, 2011
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We've lined up what we think is an amazing series of R-related webinars over the next couple of months. These free 30-60 minute webinars will cover a wide range of topics: big-data analysis in R with the RevoScaleR package, Hadoop and Netezza; introductions to R for SAS users and for R users new to Revolution R; and applications of...

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