1231 search results for "excel"

Color reduction of an image – and Warholize?

July 5, 2011
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Color reduction of an image – and Warholize?

There seems to be several methods out there for reducing the colors in an image. I became interested in this after pondering how this is done in the excellent freeware program IrfanView. Unfortunately, their method is not described anywhere that I coul...

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ARMA Models for Trading, Part VI

July 5, 2011
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ARMA Models for Trading, Part VI

All posts in this series were combined into a single, extended tutorial and posted on my new blog. In the fourth posting in this series, we saw the performance comparison between the ARMA strategy and buy-and-hold over the last approximately 10 years. Over the last few weeks (it does take time, believe me) I back-tested

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Even faster linear model fits with R using RcppEigen

Linear regression models are a major component of every applied researcher's toolbox. Obtaining results more quickly is therefore of central importance, particularly when many such models have to be fit. Common examples in this context are Monte Carl...

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The R apply function – a tutorial with examples

July 2, 2011
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Today I had one of those special moments that is uniquely associated with R. One of my colleagues was trying to solve what I term an 'Excel problem'. That is, one where the problem magically disappears once a programming language is employed. Put simpl...

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Mapping SNPs to Genes for GWAS Enrichment Analysis

June 30, 2011
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Mapping SNPs to Genes for GWAS Enrichment Analysis

There are several tools available for conducting a post-hoc analysis of GWAS data looking for enrichment of significant SNPs using literature or pathway based resources. Examples include GRAIL, ALLIGATOR, and WebGestalt among others (see SNPath R Pac...

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Two browsers for R help documentation

June 29, 2011
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Two browsers for R help documentation

The same excellent documentation for R commands is available through two different help browsers: text and HTML, and let’s see how how each looks, works, and how to switch the default. Look and feel Here is how both look for … Continue reading →

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Saving Chunks of SSURGO Data in SoilWeb for Google Earth

June 28, 2011
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Saving Chunks of SSURGO Data in SoilWeb for Google Earth

SoilWeb is an interactive, multifaceted interface to USDA-NCSS soil survey information. Our SoilWeb application for Google Earth streams soil map units and point data as you navigate across the lower '48 states. Currently, our system imposes a 30,000 ...

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p-Values for Cointegration Tests With Breaks in the Data

June 28, 2011
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p-Values for Cointegration Tests With Breaks in the Data

In an earlier post I went through some econometrics that involved the problem of testing for multivariate cointegration in the case where there are one or more trend-breaks or level-breaks in the time-series data.  Specifically, I talked about the modified Trace tests introduced by Johansen et al. (2000), and I mentioned the really nice discussion of the application of these tests...

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Confidence, Ending Equity, and What I Can Do as the Money Manager

June 24, 2011
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Confidence, Ending Equity, and What I Can Do as the Money Manager

I wrote this as my quarterly commentary, but compliance blocked it because they said I was implying that I am Warren Buffett or I can replicate Warren Buffett.  Anyways, I thought I should share it as a general discussion piece.  More than on...

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gretl

June 24, 2011
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In comments on a recent post, "Ben" and Tal Galili very sensibly asked if I could make R code available for the econometric analysis in my posts, in addition to EViews code. I'll be trying to do this wherever I can, given the time constraints.The important point implicit in these comments is that R is free, open-source, software, whereas...

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