Monthly Archives: June 2011

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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roll calls, ideal points, 112th Congress

June 29, 2011
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roll calls, ideal points, 112th Congress

Now that classes are over, I took a little time to update my scripts that update the analysis of Congressional roll calls in close to real time.   Links appear at the top of the blog.   As of about 15 minutes ago, we’re up to 77 non-unanimous roll calls in the 112th Senate.  

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A simple ggplot2 scatterplot

June 29, 2011
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Here’s a bit of code used to produce one of the figures in my recent paper dealing with modeling rocky intertidal snail body temperatures. This was my first foray into ggplot2, and it only involved a few hours of head-scratching. The plot is a co...

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Putting together multinomial discrete regressions by combining simple logits

June 29, 2011
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When predicting 0/1 data we can use logit (or probit or robit or some other robust model such as invlogit (0.01 + 0.98*X*beta)). Logit is simple enough and we can use bayesglm to regularize and avoid the problem of separation. What if there are more than 2 categories? If they’re ordered (1, 2, 3, etc),

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Stata 12 embraces structural equation models

June 28, 2011
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Stata 12 embraces structural equation models

Stata 12 has just been announced. The software will start shipping by the end of July.  A key new feature introduced in the new version is the module for structural equation models (SEM), a staple tool in marketing, psychology, and several other research disciplines.LISREL and AMOS have...

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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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Synctex with Sweave/pgfSweave in TeXShop/TeXWorks

June 28, 2011
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Ever been editing an .Rnw (Sweave) file and tried to sync a pdf with the source in TeXShop (or TeXWorks) and had it open the .tex file? This is because the synctex information (in the .synctex.gz file) is messed up. Both TeXShop and TeXWorks support synctex, that means that if everything is groovy, we should

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Benchmarking Revolution R for data mining

June 28, 2011
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Benchmarking Revolution R for data mining

The blog Heuristically Andrew puts Revolution R through its paces by running some benchmarks versus open-source R for data mining applications. The benchmarks set out to answer the following question: I recently upgraded my notebook (where I often use R for data mining) and was faced with two questions: for the fastest speed for building models, do I use...

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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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Visualizing Periodic Data

June 28, 2011
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Yesterday the Princeton machine learning reading group went through a paper by Tukey on “Some graphic and semigraphic displays”. One issue we talked about at length was Tukey’s idiosyncratic approach to visualizing periodic data in a circular format to emphasize the connections between the “start” and the “end” of the data set. Allison Chaney pointed

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