269 search results for "pca"

Computational Statistics

May 9, 2010
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Computational Statistics

Do not resort to Monte Carlo methods unnecessarily. When I received this 2009 Springer-Verlag book, Computational Statistics, by James Gentle a while ago, I briefly took a look at the table of contents and decided to have a better look later… Now that I have gone through the whole book, I can write a short

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Fun with R: Clustering and MDS

May 5, 2010
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Fun with R: Clustering and MDS

I've seen K-means clustering, PCA, etc. done some over at Beyond the Boxscore and Baseball Analysts (and the now defunct Statspeak), but I thought I'd just check out some clustering on the young fantasy season using the traditional 5x5 categories with ...

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Tipping heuristics

April 28, 2010
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Tipping heuristics

INCREDIBLY SIMPLE CALCULATIONS MADE SIMPLE Yes, we all know how to calculate 15% or 20% exactly, but it’s fun to use tipping heuristics and even more fun to make crowded graphs of how they compare to each other. (Sorry for the junky chart. Open for suggestions, in the words of Tom Waits.) Here are a

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Estimating Missing Data with aregImpute() {R}

April 19, 2010
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  Missing Data Soil scientists routinely sample, characterize, and summarize patterns in soil properties in space, with depth, and through time. Invariably, some samples will be lost or sufficient funds required for complete characterization can run out. In these cases the scientist is left with a data table that contains holes (so to speak) in the rows/columns that are...

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alphahull: an R Package for Alpha-Convex Hull

April 16, 2010
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alphahull: an R Package for Alpha-Convex Hull

new paper on the α-convex hull appeared in the Journal of Statistical Software today (http://www.jstatsoft.org/v34/i05/paper). The α-convex hull is an interesting problem which caught my attention long time ago but I didn’t know a solution then. R has a function chull() which can generate (indices of) the convex hull for a series of points. Now

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REvolution R Community 3.2 now available

April 9, 2010
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REvolution R Community, REvolution's free distribution based on R from the R Project, has been updated to version 3.2 and is now available for download for Windows and MacOS. Some features of this release include: Upgraded R engine. This release is based on R 2.10.1, the latest release (as of this writing). This brings many new features to the...

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Demonstrating the Power of F Test with gWidgets

April 2, 2010
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e know the real distribution of the F statistic in linear models — it is a non-central F distribution. Under H0, we have a central F distribution. Given 1 – α, we can compute the probability of (correctly) rejecting H0. I created a simple demo to illustrate how the power changes as other parameters vary,

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Looking for Software Paths in Windows Registry

March 28, 2010
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Looking for Software Paths in Windows Registry

hen we want to call external programs in R under Windows, we often need to know the paths of these programs. For instance, we may want to know where ImageMagick is installed, as we need the convert (convert.exe) utility to convert images to other formats, or where OpenBUGS is installed because we need this path

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A Demo for the Ratio Estimation in Sampling Survey (Animation)

March 24, 2010
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A Demo for the Ratio Estimation in Sampling Survey (Animation)

mber Watkins gave me a suggestion on the animation for the ratio estimation, and I think this is a good topic for my animation package. I’ve finished writing the initial version of the function sample.ratio() for this package, which will appear in the version 1.1-2 a couple of days later. As we know, the benefit

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Font Families for the R PDF Device

March 24, 2010
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otivated by the excellent R package pgfSweave, I begin to notice the font families in my graphs when writing Sweave documents. The default font family for PDF graphs is Helvetica, which is, in most cases (I think), inconsistent with the LaTeX font styles. Some common font families are listed in ?postscript, and we can take

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