# Blog Archives

## The Psychology of Music and the ‘tuneR’ Package

October 25, 2011
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Introduction This semester I’m TA’ing a course on the Psychology of Music taught by Phil Johnson-Laird. It’s been a great course to teach because (i) so much of the material is new to me and (ii) because the study of the psychology of music brings together so many of the intellectual tools I enjoy, including

## Twitter Math Puzzle and Solution

July 7, 2011
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Yesterday I posted a very simple math puzzle to Twitter that I found in Jonathan Baron’s book, Thinking and Deciding. The puzzle is the following: Show that every number of the form ABC,ABC is divisible by 13. The puzzle comes up in Baron’s book as an example of an “insight problem” in which one goes

## Twitter Math Puzzle and Solution

July 7, 2011
By

Yesterday I posted a very simple math puzzle to Twitter that I found in Jonathan Baron’s book, Thinking and Deciding. The puzzle is the following: Show that every number of the form ABC,ABC is divisible by 13. The puzzle comes up in Baron’s book as an example of an “insight problem” in which one goes

## 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

## ProjectTemplate News

June 25, 2011
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The news below was recently reported on the ProjectTemplate mailing list. For completeness, I’m also reporting it here. The first piece of ProjectTemplate news is that I won’t be the exclusive maintainer for ProjectTemplate anymore. Allen Goodman, who works at BankSimple, is now my co-maintainer and he has full commit privileges. In the next few

## Speeding Up MLE Code in R

June 18, 2011
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Recently, I’ve been fitting some models from the behavioral economics literature to choice data. Most of these models amount to non-linear variants of logistic regression in which I want to infer the parameters of a utility function. Because several of these models aren’t widely used, I’ve had to write my own maximum likelihood code to

## Norvig and the Nature of Modern Science

May 27, 2011
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In this, Chomsky is in complete agreement with O’Reilly. (I recognize that the previous sentence would have an extremely low probability in a probabilistic model trained on a newspaper or TV corpus.)1 Anyone who considers themself an intellectual should be required to read this new essay by Peter Norvig. It’s the best summary I’ve ever

## Problems with ggplot2 0.8.9 and R 2.13.0 on Mac OS X via plyr 1.5

April 14, 2011
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This morning I tried to completely update my R installation. I first dumped a list of all the packages I have on my system using the installed.packages() function. Then I installed R 2.13.0 using the OS X disk image. And finally I reinstalled all of my packages from scratch. Unfortunately, I ran into some serious

## A Request for Foursquare Data

March 25, 2011
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I’m trying to collect data sets that showcase how the classical statistical distributions appear in modern contexts. I’ve already got some data that shows how the gamma distribution appears in video game scores, and now I’m hoping to find an example where the exponential distribution

## A 3D Version of R’s curve() Function

March 21, 2011
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I like exploring the behavior of functions of a single variable using the curve() function in R. One thing that seems to be missing from R’s base functions is a tool for exploring functions of two variables. I asked for examples of such a function on Twitter today and didn’t get any answers, so I

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