Monthly Archives: October 2011

permute: a package for generating restricted permutations

October 4, 2011
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permute: a package for generating restricted permutations

Multivariate ordination methods are commonly used in ecology to investigate patterns in species composition in space or time. Constrained ordination methods such as redundancy analysis (RDA) and canonical correspondence analysis (CCA) are effectively just multiple regressions, but we lack the parametric theory to adequately test the statistical significance of terms in the model. Other techniques likewise lack the appropriate...

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How to show explained variance in a multilevel model

October 3, 2011
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How to show explained variance in a multilevel model

In this post I will show one way to display explained variance using a line chart. There is no default plot for displaying the effect of each factor on deviance of the model, so this is a tentative proposal for my dissertation. The following values were obtained using multilevel models performed in R (thanks for

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Oracle’s Big Data Appliance to include R

October 3, 2011
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At the Oracle OpenWorld conference in San Francisco today, Oracle announced the new Oracle Big Data Appliance, "a new engineered system that includes an open source distribution of Apache™ Hadoop™, Oracle NoSQL Database, Oracle Data Integrator Application Adapter for Hadoop, Oracle Loader for Hadoop, and an open source distribution of R." Oracle's foray into the Hadoop and NoSQL spaces...

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Visualizing Climbing Ropes

October 3, 2011
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Visualizing Climbing Ropes

Today’s market of climbing ropes offers a huge variety of models to choose from. If you don’t have a good idea of what you want, the task of selecting a rope can become a true challenge, or worst, almost a … Continue reading →

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The four steps to publication-grade graphics in R

October 3, 2011
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This Article is also available in EN, ES.

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OLS beta VS. Robust beta

October 3, 2011
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OLS beta VS. Robust beta

In financial context, is suppose to reflect the relation between a stock and the general market. A broad based index such as the S&P 500 is often taken as proxy for the general market. The , without getting into too … Continue reading →

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Twitter updates on R Graph Gallery

October 3, 2011
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Twitter updates on R Graph Gallery

I've added a twitter search widget that searches for the #rgraphgallery hashtag or the url of the gallery on the front page.

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Predictability of kurtosis and skewness in S&P constituents

October 3, 2011
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Predictability of kurtosis and skewness in S&P constituents

How much predictability is there for these higher moments? Data The data consist of daily returns from the start of 2007 through mid 2011 for almost all of the S&P 500 constituents. Estimates were made over each half year of data.  Hence there are 8 pairs of estimates where one estimate immediately follows the other. … Continue reading...

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Model Exploration using K-sample Plot in Big Data

October 3, 2011
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Model Exploration using K-sample Plot in Big Data

Generically, error rate of predicting binary variable by a certain model becomes plateau increasing sample size. When the model fits training data , the error rate gains from 0 to true error. And when the model fits test data, the error rate decreases ...

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Visual Illusions: Google vs Facebook vs Yahoo

October 3, 2011
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Visual Illusions: Google vs Facebook vs Yahoo

The ability to visualize data, enabled by the advent of graphical computer tools, has been a great boon to Cap and Perf. The power derives from the way graphical displays provide an efficient impedance match to the visual system in our brain. The weakness derives from the way graphical displays provide an efficient impedance match to the visual system...

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