# Monthly Archives: January 2013

## Maps in R: Plotting data points on a map

January 10, 2013
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In the introductory post of this series I showed how to plot empty maps in R. Today I'll begin to show how to add data to R maps. The topic of this post is the visualization of data points on … Continue reading →

January 9, 2013
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The go-to bible for this data scientist and many others is The Elements of Statistical Learning: Data Mining, Inference, and Prediction by Trevor Hastie, Robert Tibshirani, and Jerome Friedman. Each of the authors is an expert in machine learning / prediction, and in some cases invented the techniques we turn to today to make sense of big data: ensemble...

## Every NFL punt since 2002

January 9, 2013
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The site reddit told us about data on every single NFL (U.S. National Football League) play since 2002. We read it in and did an analysis of punting. The results are beautiful. The post Every NFL punt since 2002 appeared first on Decision Science News.

January 9, 2013
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## Revisiting Cronbach 1951 via Simulation with Shiny

January 9, 2013
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At the time of the creation of this blog, Cronbach’s 1951 piece on coefficient alpha has 18,132 citations according to google scholar.  The main use of coefficient alpha is to assess internal consistency reliability of a test or survey.   Although it may have been forgotten, the proof Cronbach demonstrated established that coefficient alpha is the mean of all split...

## Revisiting Cronbach 1951 via Simulation with Shiny

January 9, 2013
By

At the time of the creation of this blog, Cronbach’s 1951 piece on coefficient alpha has 18,132 citations according to google scholar.  The main use of coefficient alpha is to assess internal consistency reliability of a test or survey.   Although it may have been forgotten, the proof Cronbach demonstrated established that coefficient alpha is the mean of all split...

## Factor Analysis of Baseball’s Hall of Fame Voters

January 9, 2013
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Factor Analysis of Baseball's Hall of Fame VotersRecently, Nate Silver wrote a post which analyzed how voters who voted for and against Barry Bonds for Baseball's Hall of Fame differed. Not surprisingly, those who voted for Bonds were more likely to vote for other suspected steroids users (like Roger Clemens). This got...

## WordPress Stats in R

January 9, 2013
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A trackback from Martin Hawksey’s recent post on Analysing WordPress post velocity and momentum stats with Google Sheets (Spreadsheet), which demonstrates how to pull WordPress stats into a Google Spreadsheet and generates charts and reports therein, reminded me of the WordPress stats API. So here’s a quick function for pulling WordPress reports into R. (Code

## First steps in using C++11 with Rcpp

January 9, 2013
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The recent release of the C++11 standard has brought a lot of attention to the new language features. Rcpp, as a CRAN package, follows CRAN policy in not (yet!!) supporting the standard for its purported non-portable status. Even as of the current g++ ...

## Item Response Modeling of Customer Satisfaction: The Graded Response Model

January 8, 2013
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After several previous posts introducing item response theory (IRT), we are finally ready for the analysis of a customer satisfaction data set using a rating scale.  IRT can be multidimensional, and R is fortunate to have its own package, mirt, with excellent documentation (R.Philip Chalmers).  But, the presence of a strong first principal...