Blog Archives

Doing Maximum Likelihood Estimation by Hand in R

April 21, 2010
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Doing Maximum Likelihood Estimation by Hand in R

Lately I’ve been writing maximum likelihood estimation code by hand for some economic models that I’m working with. It’s actually a fairly simple task, so I thought that I would write up the basic approach in case there are readers who haven’t built a generic estimation system before. First, let’s start with a toy example

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The Price of Calculation

March 15, 2010
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In a world in which the price of calculation continues to decrease rapidly, but the price of theorem proving continues to hold steady or increase, elementary economics indicates that we ought to spend a larger and larger fraction of our time on calculation.1 Over the next ten years, I hope that more and more mathematically

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Gay Marriage: Another Data Point

January 16, 2010
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Relevant to my earlier post about the relationship between direct democracy and laws prohibiting gay marriage, Pew Research just published poll data showing that a majority of Americans disapprove of same-sex marriage.

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Academics’ Slang: Orthogonal

January 12, 2010
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H. G. Wells famously said that, “statistical thinking will one day be as necessary for efficient citizenship as the ability to read and write.” I think we’re getting closer to that day: even the Supreme Court of the United States plan...

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Outlawing Gay Marriage

January 10, 2010
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Given the recent votes on same-sex marriage in New Jersey and Portugal, I wanted to test a seemingly innocuous claim that touches upon very broad issues in political theory: does the degree of directness of a “democratic” vote predict whether the vote will promote or prohibit same-sex marriage? Naively, it seemed clear to me that

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Killing Yourself: An Addendum

January 9, 2010
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In further support of the claim that a lot of deaths are partly self-induced, here’s a fascinating piece by Wired on the extraordinary rise in the percent of deaths among the young caused by their own poor decisions. It’s remarkable that, for the young, modern science has already made the world so safe that humanity,

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Announcing r-ORM: A Pure R Object-Relational Mapper

January 5, 2010
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My apologies for the long break between posts. Before the end of this week I’ll return to my series of posts on image processing in R. In the intervening time, I’ve finished a piece of code that I’d like to officially release to the public. The code in question is a very minimal object-relational mapper

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Using Complex Numbers in R

December 18, 2009
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Using Complex Numbers in R

This post is a continuation of my series dealing with matrix operations for image processing. My next goal is to demonstrate the construction of simple low-pass and high-pass spatial frequency filters in R. It’s easy enough to construct simple versions of these filters in R using the Fast Fourier Transform (also known as the FFT),

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Image Compression with the SVD in R

December 17, 2009
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Image Compression with the SVD in R

Over the next few posts, I’m going to be reviewing the use of R to implement the most commonly used matrix techniques for image manipulation. The code will be surprisingly simple to understand, because the real magic behind these techniques lies in the mathematics that R provides an abstract interface to. To start, I’m going

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Quick Review of Matrix Algebra in R

December 16, 2009
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Lately, I’ve been running a series of fMRI experiments on visual perception. In the interests of understanding the underlying properties of the images I’m using as stimuli, I’ve been trying to learn more about the matrix transformations commonly used for image compression and image manipulation. Thankfully, R provides simple-to-use implementations for all of the matrix

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