Monthly Archives: February 2010

The R type system

February 21, 2010
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The R type system

R is a weird beast. Through it's ancestor the S language, it claims a proud heritage reaching back to Bell Labs in the 1970's when S was created as an interactive wrapper around a set of statistical and numerical subroutines. As a programming language,...

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The truncated Poisson

February 21, 2010
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The truncated Poisson

A common model for counts data is the Poisson. There are cases however that we only record positive counts, ie there is a truncation of 0. This is the truncated Poisson model. To study this model we only need the total counts and the sample size. This comes from the sufficient statistic principle as the

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Visual Interpretation of Principal Coordinates (of) Neighbor Matrices (PCNM)

February 21, 2010
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Principal Coordinates (of) Neighbor Matrices (PCNM) is an interesting algorithm, developed by P. Borcard and P. Legendre at the University of Montreal, for the multi-scale analysis of spatial structure. This algorithm is typically applied to a distance matrix, computed from the coordinates where some environmental data were collected. The resulting "PCNM vectors" are commonly used to describe...

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Uh!

February 20, 2010
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Didn't know this... a data 0 2 4 7+ 25 34 12 5 It's becoming clear that I have learned R in the most unstructured way...I always do it in two stages :ashamed:

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Design of Experiments – Block Designs

February 20, 2010
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Design of Experiments – Block Designs

In many experiments where the investigator is comparing a set of treatments there is the possibility of one or more sources of variability in the experimental measurements that can be accounted for during the design stage of the experimentation. For example we might be investigating four different pieces of machinery using say two different operators,

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Does a Proclamation of Increased Workout Load Matter?

February 20, 2010
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Does a Proclamation of Increased Workout Load Matter?

I forgot to link this up, but I have a new article (joint with our editor) over at Fantasy Ball Junkie. I run an extremely crude model to see if players who were mentioned in the media as having lost weight, gained muscle, gained speed, got eye surgery...

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Genetic Algorithm Systematic Trading Development — Part 3 (Python/VBA)

February 20, 2010
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Genetic Algorithm Systematic Trading Development — Part 3  (Python/VBA)

As mentioned in prior posts, it is not possible to use the standard Weka GUI to instantiate a Genetic Algorithm, other than for feature selection. Part of the reason is that there is no generic algorithm to instantiate a fitness function. The same fl...

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lme4 stands 4 Linear mixed-effects…

February 19, 2010
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lme4 stands 4 Linear mixed-effects…

There is a certain hype about mixed (and random) effects among statistician and analysts. You can show some love to Douglas Bates and Martin Maechler for maintaing the lme4 package for our cupid, R I copy the entity of the information of the projects page. Doxygen documentation of the underlying C functions is here. The

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R exam postprocessing

February 19, 2010
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R exam postprocessing

Following my three-fold R exam of last month, I had a depressing afternoon meeting (with other faculty members) some students who had submitted R codes that were suspiciously close to other submitted R codes… In other words, it looked very  likely they had cheated. (A long-term issue with my R course, alas!) During this meeting,

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Where did all the bankers go?

February 19, 2010
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Where did all the bankers go?

When Lehman Brothers, Bear Stearns and Merrill Lynch went kablooie in the financial crisis, what happened to all their employees? Thanks to the magic of LinkedIn data, their Chief Scientist DJ Patil can answer that question: they went to the surviving banks: It's a great, if tantalizingly incomplete visualization -- I'd love to see this with "Other (non-bank) employers"...

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