Simpson’s Paradox

July 20, 2011
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Simpson’s Paradox

A few days ago I heard a talk about Simpson's paradox, and I decided to write a little example in R:library(MASS) # For multivariate normals# List of (vectors of) meansmu <- list(c(5, 175), c(6.25, 110))# List of covariance matricessigma ...

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Visualizing Kickstarter Projects with R

July 20, 2011
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Visualizing Kickstarter Projects with R

Kickstarter, a social funding platform where individuals can chip in cash to get a worthy project going, just celebrated their 10,000th kickstarted project. Kickstart employee Fred Benenson recognized the achievement by visualizing the funding of music, design, art, game and many other kinds of projects using R and ggplot2. For example, here's a chart that shows the increasing rate...

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Showcasing the latest phylogenetic methods: AUTEUR

July 20, 2011
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Showcasing the latest phylogenetic methods: AUTEUR

While high-speed fish feeding videos may be the signature of the lab, dig a bit deeper and you’ll find a wealth of comparative phylogenetic methods sneaking in.  It’s a natural union — expert functional morphology is the key to good … Continue reading →

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Shorting Mebane Faber

July 19, 2011
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Shorting Mebane Faber

Although I do not personally know Mebane Faber, I know enough that I do not want to short him. However, I thought it would be insightful to see how the short side of his “A Quantitative Approach To Tactical Asset Allocation” might look.  Once ...

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The Road to Default: The Other Side of the Story

July 19, 2011
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The Road to Default: The Other Side of the Story

Okay so I was gliding through the articles of CNBC.com and stumbled upon one titled, "A Downgrade of U.S. Debt Won't Matter as Much as You Think." The argument laid down in this piece is that insurance companies and pension funds are required to hold h...

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Looking for NppToR beta testers.

July 19, 2011
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NppToR 2.6 is coming with improved flexibility and speed. Testers needed before setting as default.

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Version 1.3 Verified

July 19, 2011
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Version 1.3 Verified

Whew, For a few hours last night I struggled with a bug, err several bugs. In the end some of the bugs were mine, some of them were “upstream” and some of them were  far “upstream”.  Image  bugs in R 2.13.1. But the math bugs ( or flat out errors on my part) have all

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Growth in data-related jobs

July 19, 2011
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Growth in data-related jobs

At job-search site indeed.com, you can take a look at trends in the use of keywords used in job postings. As you might expect, job postings containing terms related to making sense from data are on the rise. Here's the growth in job postings mentioning big data: And here's statistician: The drop-off in demand for statisticians 2011 seems to...

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Extracting EOD Data from BSE

July 19, 2011
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Extracting EOD Data from BSE

Earlier, I had worked around to download Bhavcopy from NSE. Now, I would make a similar attempt to download the BSE BhavcopyObjective: Download Bhavcopy (Equity) from http://www.bseindia.com and save only relevant columns Date, Symbol, Name, Open, High...

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Extracting EOD Data from NSE

July 19, 2011
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Extracting EOD Data from NSE

My prime interest being the Indian financial markets, the first step would be to get the data to play around. NSE India provides EOD of data as bhavcopies. The same are stored as zipped files at their servers. Downloading them one by one for a larger t...

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Geocoding addresses from Missouri Sex Offender Registry

July 19, 2011
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Computer Assisted Reporting This is the second of four articles about analyzing distances between sex offenders and child daycare centers in Missouri as part of a joint project with KSHB NBC Action News in Kansas City. The previous article gave details...

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Analysis of Missouri Sex Offender Registry Data

July 18, 2011
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Computer Assisted Reporting This is the first of three articles about analyzing distances between sex offenders and child daycare centers in Missouri as part of a joint project with KSHB NBC Action News in Kansas City. The Missouri State Highway Patrol...

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The foundations of Statistics [reply]

July 18, 2011
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The foundations of Statistics [reply]

Shravan Vasishth has written a response to my review both published on the Statistics Forum. His response is quite straightforward and honest. In particular, he acknowledges not being a statistician and that he “should spend more time studying statistics”. I also understand the authors’ frustration at trying “to recruit several statisticians (at different points) to

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GigaOm article on R, Big Data and Data Science

July 18, 2011
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I'm really pleased that an article I wrote, "5 real-world uses of big data", has been published in the widely-read technology blog GigaOm. In the article, I review five examples of using data science techniques and R to make sense of some large real-world data sets: Drew Conway's analysis of the Afghanistan attacks data released by Wikileaks Benetech's use...

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Registration closing for UseR! 2011

July 18, 2011
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Registration closing for UseR! 2011

Friday July 22 is the last day on which you can register for UseR! 2011 at the University of Warwick.  The conference will be 2011 August 16-18. You can peruse the book of abstracts and view the draft schedule. I am scheduled to give a talk on “Random input testing with R”.  The abstract is: … Continue reading...

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Model Validation: Interpreting Residual Plots

July 18, 2011
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Model Validation: Interpreting Residual Plots

When conducting any statistical analysis it is important to evaluate how well the model fits the data and that the data meet the assumptions of the model. There are numerous ways to do this and a variety of statistical tests to evaluate deviations from model assumptions. However, there is little general acceptance of any of the statistical tests. Generally...

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Example 9.3: augmented display of contingency table

July 18, 2011
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Example 9.3: augmented display of contingency table

SAS and R often provide different levels of details from output. This is particularly true for the descriptive analysis of contingency tables, where SAS makes it easy to display tables with additional quantities (such as the observed cell count).The m...

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The Road to Default: Puppy Power!

July 18, 2011
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The Road to Default: Puppy Power!

Although Congress can technically dilly dally until August 2nd to come up with an agreement and raise the debt ceiling- markets have anticipated the inevitable. They haven't sat back and decided to wait till August 2nd to panic- they are already in "oh...

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Fast logistic regression on Big Data with commodity hardware? No problem.

July 18, 2011
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You might think that doing advanced statistical analysis on Big Data is out of reach for those of us without access to expensive hardware and software. For example, back in April SAS was proud to demonstrate being able to run logistic regression on a billion records (and "just a few" variables) in less than 80 seconds. But that feat...

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Avoiding Loops in R: An Example with Principal Minors

July 18, 2011
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Avoiding Loops in R: An Example with Principal Minors

Yesterday, I found myself wanting to compute a large subset of the second order principal minors of a matrix (diagonal-preserving minors; the ones for which the rows and columns kept are the same). Don't judge me for wanting to do this, and bear with ...

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1st Data Analysis Contest Using R

1st Data Analysis Contest Using R

Emilio Torres Manzanera has just announced the 1st Data Analysis Contest Using R: “Nestoria (http://www.nestoria.com/) is a specialized web search engine platform in house prices. Nestoria and Lokku Labs aim to improve the understanding of the public of the value of its databases. The company aims to engage a few brilliant statisticians in the expectation

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On “Stock correlation has been rising”

July 17, 2011
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On “Stock correlation has been rising”

Ticker Sense posted about the mean correlation of the S&P 500. The plot there — similar to Figure 1 — shows that correlation has been on the rise after a low in February. Figure 1: Mean 50-day rolling correlation of S&P 500 constituents to the index. For me, this post raised a whole lot more … Continue reading...

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The method in the mirror: reflection in R

July 17, 2011
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The method in the mirror: reflection in R

Reflection is a programming concept that sounds scarier than it is. There are three related concepts that fall under the umbrella of reflection, and I’ll be surprised if you haven’t come across most of these code ideas already, even if you didn’t know it was called reflection. The first concept is examination of your variables.

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Correlation Resources: SPSS, R, Causality, Interpretation, and APA Style Reporting

July 17, 2011
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This post provides links to a range of resources related to the use and interpretation of correlations. I wanted to provide a page with links to a number of additional resources that would be useful both for those of my students who might be keen to le...

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Migrating from SPSS/Excel to R, Part 2: Working with Packages

July 17, 2011
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Migrating from SPSS/Excel to R, Part 2: Working with Packages

In this post, I cover an important aspect of using R that users of SPSS/Excel won’t be familiar with: working …Continue reading »

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Accepted lack of confidence

July 17, 2011
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Accepted lack of confidence

I just got the following email from PNAS about our Lack of confidence in ABC model choice. Editor's Remarks to Author: both referees now find the manuscript acceptable for publication as do I. Each suggests small changes which I encourage the authors to make prior to having the manuscript go into production. Congratulations on an

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The Road to Default: Deep DooDoo

July 16, 2011
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The Road to Default: Deep DooDoo

Okay so what is the situation at hand? Well the inevitable default of the United States of course.  The U.S. will default regardless of whether Congress raises the debt ceiling. You may be thinking the following: But how can he say such a thing? I...

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Mixture distributions and models: a clarification

Mixture distributions and models: a clarification

In response to my last post, Chris had the following comment:           I am actually trying to better understand the distinction between mixture models and mixture distributions in my own work.  You seem to say mixture models apply to a small set of models – namely regression models.This comment suggests that my caution about the difference between mixed-effect models and mixture distributions...

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Slopegraphs in R

July 16, 2011
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Slopegraphs in R

The internet seems abuzz this week with the "discovery" of a long-lost Edward Tufte plot type: the slopegraph. In this post, I'll show you how to create these elegant compact plots using R and ggplot2.

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