From Lavaan to OpenMx

October 2, 2012
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From Lavaan to OpenMx

Joel Caldwell gave an example of Confirmatory factor analysis in lavaan. The purpose of this post is to show you how to express this model in OpenMx. The data being modeled are in an object called ratings (see below for the code to create this object as described here. Here’s Joe’s example structural equation model, as implemented in lavaan: require(lavaan) bifactor <- "general.factor =~ Easy_Reservation +...

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R for SAS, SPSS, Stata Users Workshop Redesigned

October 2, 2012
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R for SAS, SPSS, Stata Users Workshop Redesigned

My workshop R for SAS, SPSS and Stata Users has been popular over the years, but it’s time for an overhaul. A common request has been to simplify it, so I have moved data management to a separate 4-hour workshop, … Continue reading →

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A replacement for theme_blank()

October 2, 2012
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A replacement for theme_blank()

ggplot2 has just hit 0.9.2, and with the change comes a new theme system. Previous versions of ggplot2 offered a theme_blank(), which was a stripped-down, essentially blank plotting canvas, but it is now deprecated. github user jrnold has produced a s...

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“Advanced R” Course – November 15-16, 2012

October 2, 2012
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This two days course shows wide variety of “Advanced R” topics ranging from S4 methods and classes to parallel computing in order to provide an exhaustive overview of R capabilities. Continue reading →

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Connecting the real world to R with an Arduino

October 2, 2012
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Connecting the real world to R with an Arduino

If connecting data to the real world is the next sexy job, then how do I do this? And how do I connect the real world to R? It can be done as Matt Shottwell showed with his home made ECG and a patched version of R at useR! 2011. However, there are ot...

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Scraping pages and downloading files using R

October 1, 2012
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Scraping pages and downloading files using R

I have written a few posts discussing descriptive analyses of evaluation of National Standards for New Zealand primary schools.The data for roughly half of the schools was made available by the media, but the full version of the dataset is … Continue reading →

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analyze the area resource file (arf) with r

October 1, 2012
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the arf is fun to say out loud.  it's also a single county-level data table with about 6,000 variables, produced by the united states health services and resources administration (hrsa).  the file contains health information and statistics fo...

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Where in the world is R and RStudio

October 1, 2012
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Where in the world is R and RStudio

Using the web logs collected when users download RStudio, we’ve prepared the following two maps showing where RStudio is being used, over the whole globe and just within the continental USA. Obviously this data is somewhat biased, as it reflects the number of downloads of RStudio, rather than the number of users of R (which

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Ordinal football

October 1, 2012
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Ordinal football

I've had a quick look at this article on R-bloggers $-$ I don't think I've followed the whole exchange, but I believe they have discussed what models should/could be applied to estimate football scores (specifically, in this case they are using the Dut...

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Designing real-world 3-D objects with R

October 1, 2012
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Designing real-world 3-D objects with R

The Maker Movement has led to the production of open-source 3-D printers and other manufacturing machines that allow hobbyists to design, create and produce real-world objects affordably. Now R user Ian Walker, in a post at the Psychological Statistics blog, shows how to use the R language to transform 3-D surfaces into real-world physical objects with a 3-D printer....

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A Brief Tip on Generating Fractional Factorial Designs in R

October 1, 2012
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A number of marketing researchers use the orthoplan procedure in SPSS to generate fractional factorial designs.  It is not surprising, then, that I received a number of questions concerning the recent article in the Journal of Statistical Software by Hideo Aizaki on “Basic Functions for Supporting an Implementation of Choice Experiments in R.”  To summarize their issues,...

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Example 10.4: Multiple comparisons and confidence limits

October 1, 2012
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Example 10.4: Multiple comparisons and confidence limits

A colleague is a devotee of confidence intervals. To him, the CI have the magical property that they are immune to the multiple comparison problem-- in other words, he feels its OK to look at a bunch of 95% CI and focus on the ones that appear to exclude the null. This though...

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When Russell 2000 is Low Vol

October 1, 2012
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When Russell 2000 is Low Vol

Continuing in my exploration of the Russell 2000 (Russell 2000 Softail Fat Boy), I thought I would try to approach the topic with a low volatility paradox mindset.  Since 2005, beta of the Russell 2000 compared to the S&P 500 has exceeded 1.2 ...

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Level fit summaries can be tricky in R

October 1, 2012
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Level fit summaries can be tricky in R

Model level fit summaries can be tricky in R. A quick read of model fit summary data for factor levels can be misleading. We describe the issue and demonstrate techniques for dealing with them.When modeling you often encounter what are commonly called categorical variables, which are called factors in R. Possible values of categorical variables Related posts:

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How does my computer know what language I am using? – An approach of statistical learning (Language, Computer Science)

October 1, 2012
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How does my computer know what language I am using? – An approach of statistical learning (Language, Computer Science)

Quick and Easy Subsetting

October 1, 2012
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Quick and Easy Subsetting

Public health datasets can be enormous and difficult to look at.  Often it is great to be able to only look at specific parts of the dataset, or to only run analysis on a specific part of a dataset.  There are two ways that you can subset a d...

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Rcpp 0.9.14

October 1, 2012
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Another release of Rcpp has just appeared on CRAN and was just uploaded to Debian. It addresses yet another issue we had on OS X and should hopefully put the build issues to rest. Three new (vectorized) sugar functions were added, along with some ne...

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Making random, equally-sized partitions

October 1, 2012
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Making random, equally-sized partitions

Sometimes, as with cross-validation, one needs to generate k partitions, each with an equal number of observations. There are probably an infinite number of ways this could be done in R, but the Gist below illustrates one way to do it in four lines, w...

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How to add a benchmark to a variance matrix

October 1, 2012
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How to add a benchmark to a variance matrix

There is a good way and a bad way to add a benchmark to a variance matrix that will be used for optimization and similar operations.  Our examination sheds a little light on the process of variance matrix estimation in this realm. Role of benchmarks Investing Benchmarks are common in investment management.  It’s my opinion … Continue reading...

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Fitting an ellipse to point data

September 30, 2012
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Fitting an ellipse to point data

Some time ago I wrote an R function to fit an ellipse to point data, using an algorithm developed by Radim Halíř and Jan Flusser1 in Matlab, and posted it to the r-help list. The implementation was a bit hacky, returning odd results for some data. A couple of days ago, an...

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An R-based Research Notebook – Test

September 30, 2012
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The following are from Tom Torsney-Weir’s blog (here’s the repo). Simple MathJax and R example A more complex example with caching <!--begin.rcode test2,cache=TRUE x.vals <- runif(10) y.vals Another plotting example using ggplot <!--begin.rcode test3,cache=TRUE, message=FALSE library(ggplot2) c Example using googleVis <!--begin.rcode test4,cache=TRUE, message=FALSE, results='asis' suppressPackageStartupMessages(library(googleVis)) ## Table with embedded links PopTable

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Working with Bipartite/Affiliation Network Data in R

September 30, 2012
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Working with Bipartite/Affiliation Network Data in R

Data can often be usefully conceptualized in terms affiliations between people (or other key data entities). It might be useful analyze common group membership, common purchasing decisions, or common patterns of behavior. This post introduces bipartite/affiliation network data and provides … Continue reading →

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Football, an ordinal model

September 30, 2012
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Football, an ordinal model

On September 19th, flo2speak remarked under a post that his/her experience is that ordinal models had better performance. That seems reason enough to try, so there we are. In examining this type of model it is found that more complex models can be...

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Plot R Data With googleVis

September 30, 2012
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Here is a little code snippet that shows how to do two things Use the Google Maps API to resolve place names into lat-long coordinate pairs. Plot R dataframes that contain lat-long data (for example from #1) onto Google Maps for quick visualization using the googleVis package.  The embedded map looks a little wonky here but it looks...

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Quantifying student feedback using Org mode and R

September 30, 2012
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Quantifying student feedback using Org mode and R

As the term has progressed, my LSM2241 lectures are getting more consistent. I’m aiming to use 45 slides for what is officially a two hour lecture, although in reality it lasts about 90 minutes. We take a break at about 50 … Continue reading →

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my Facebook social network

September 29, 2012
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my Facebook social network

I got very excited on making a network diagram of my Facebook network using Ghefi (https://gephi.org/) and submitted my first assignment for the Social Network Analysis course on https://www.coursera.org/. It's middle of the night, so I will ...

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Padding integers for use in filenames

September 29, 2012
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Padding integers for use in filenames

If you’ve ever written code that generates a whole whack of files, you may have came across the following problem when processing them. Using a naming convention wherein files are numbered will  gum up any ordering which is based on string sorting (ls, for example). What you end up with is something like this: Which

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Merging Dataframes by Partly Matching String

September 29, 2012
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The latest posting by Tony Hirst sparked my attention because I was thinking about a very similar issue recently.I was also fiddling around with agrep and adist until I realised that for this very issue matching of substrings is not as important as matching multiple words.. With this different approach I quite easily matched all but 3...

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Weekend Reading – Gold in October

September 28, 2012
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Weekend Reading – Gold in October

I recently came across the “An early Halloween for gold traders” article by Mark Hulbert. I have discussed this type of seasonality analysis in my presentation at R/Finance this year. It is very easy to run the seasonality analysis using the Systematic Investor Toolbox. This confirms that October have been historically bad for Gold, but

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