Monthly Archives: June 2012

Sleep – Part II

June 27, 2012
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Sleep – Part II

Still gettin' it? I'm off to Montreal for Jazzfest.

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PluginR in mods.tiki.org updated

June 27, 2012
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PluginR in mods.tiki.org updated

PluginR has been updated in mods.tiki.org. So what? Do I need to update my PluginR? How can I do it? PluginR resides in a subversion (svn) repository in sourceforge.net. Files can be fetched at any time by anyone using svn (see details in http://de...

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Access data quickly and easily: data.table package

June 27, 2012
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This article gives a brief overview of the data.table package written by M. Dowle, T. Short, S. Lianoglou. A data.table is an extension of a data.frame created to reduce the working time of the user in two ways programming time … Continue reading →

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Effect of sample size on the accuracy of Cohen’s d estimates (95 % CI)

June 27, 2012
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Effect of sample size on the accuracy of Cohen’s d estimates (95 % CI)

When talking about confidence intervals, Jacob Cohen famously said: “I suspect that the main reason they are not reported is that they are so embarrassingly large!” (Cohen, 1994). In this post I'll take a look at the relationship between the 95 % CI for Cohen's d and it's corresponding sample size.

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Effect of sample size on the accuracy of Cohen’s d estimates (95 % CI)

June 27, 2012
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Effect of sample size on the accuracy of Cohen’s d estimates (95 % CI)

Introduction I've been incredibly busy the last month, amongst other things I've moved about 400 miles from Umeå, in the north of sweden, to Stockholm. However, I've been working a lot with R and especially with power analysis both via Monte Carlo simulations and via analytical approaches. I will not write about power analysis here, but I will write about a closely related concept about...

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Solving Big Problems with Oracle R Enterprise, Part II

June 27, 2012
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Solving Big Problems with Oracle R Enterprise, Part II

Part II – Solving Big Problems with Oracle R Enterprise In the first post in this series (see https://blogs.oracle.com/R/entry/solving_big_problems_with_oracle), we showed how you can use R to perform historical rate of return calculations against investment data sourced from a spreadsheet.  We demonstrated the calculations against sample data for a small set of accounts.  While this worked...

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Factor Attribution 2

June 26, 2012
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Factor Attribution 2

I want to continue with Factor Attribution theme that I presented in the Factor Attribution post. I have re-organized the code logic into the following 4 functions: factor.rolling.regression – Factor Attribution over given rolling window factor.rolling.regression.detail.plot – detail time-series plot and histogram for each factor factor.rolling.regression.style.plot – historical style plot for selected 2 factors factor.rolling.regression.bt.plot

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Figuring an exchange rate for sports scores

June 26, 2012
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While the US's Major League Soccer is using advanced analytics to analyze ball movement and improve team composition, they might want to think about a smaller, but possibly more impactful, goal for analytics. Like, how to explain to an American audience what a 1-2 game means to a basketball or baseball fan not familiar with scoring in the beautiful...

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Blog with R Markdown and tumblr: Part II

June 26, 2012
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Blog with R Markdown and tumblr: Part II

In Part I of this series I described how to set up your tumblr blog so that you can create posts like those on the example site R Markdown Blog. Now I’ll describe how you can actually create such posts. I’ll be using the RStudio IDE for the desktop in all the steps below,...

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Crazy RUT in Academic Context Why Trend is Not Your Friend

June 26, 2012
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Crazy RUT in Academic Context Why Trend is Not Your Friend

In response to Where are the Fat Tails?, reader vonjd very helpfully referred me to this paper The Trend is Not Your Friend! Why Empirical Timing Success is Determined by the Underlying’s Price Characteristics and Market Efficiency is Irrelevant by P...

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