Emulating dynamic scoping in GNU R

July 21, 2012
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By design GNU R uses lexical scoping. Fortunately it allows for at least two ways to simulate dynamic scoping.Let us start with the example code and next analyze it:x <- "global"f1 <- function() cat("f1:", x, "\n")f2 <- function() cat("f2:", e...

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The Amazing Mean Shift Algorithm

July 21, 2012
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The Amazing Mean Shift Algorithm

The mean shift algorithm is a mode-based clustering method due to Fukunaga and Hostetler (1975) that is commonly used in computer vision but seems less well known in statistics. The steps are: (1) estimate the density, (2) find the modes of the density, (3) associate each data point to one mode. 1. The Algorithm We [...]

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Le Monde puzzle [#783]

July 20, 2012
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Le Monde puzzle [#783]

In a political party, there are as many cells as there are members and each member belongs to at least one cell. Each cell has five members and an arbitrary pair of cells only shares one member. How many members are there in this political party? Back to the mathematical puzzles of Le Monde (science [...]

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Interview with Lauren Talbot – Quantitative analyst for the NYC Financial Crime Task Force

July 20, 2012
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Interview with Lauren Talbot – Quantitative analyst for the NYC Financial Crime Task Force

Lauren Talbot Lauren Talbot is a quantitative analyst for the New York City Financial Crime Task Force. Before working for NYC she was an analyst at Acumen LLC and got her degree in economics from Stanford University. She is a key player turning spa...

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Likelihood thresholds and decisions

July 20, 2012
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David Hogg points me to this discussion: Martin Strasbourg and I [Hogg] discussed his project to detect new satellites of M31 in the PAndAS survey. He can construct a likelihood ratio (possibly even a marginalized likelihood ratio) at every position in the M31 imaging, between the best-fit satellite-plus-background model and the best nothing-plus-background model. He [...]

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Do to other as you would have them do to you

July 20, 2012
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The New York Times wrote about how the "Big Data" industry is trying to transform education (link). This is amusing and creepy by turns. All of these may be well-intentioned, but what strikes me is how unscientific the arguments are given in favor of these data-driven methods. You'd expect the same data-driven approach to be used to justify their new solutions but you find almost none of that. *** For…

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Course at Monash (#2)

July 19, 2012
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Course at Monash (#2)

Here are the slides for the second day of my course at Monash University, Melbourne, in the Special Lectures in Econometrics, with a strong strong similarity with the slides of my course in Roma this Spring. (Ah, sunny Roma…) The first day lecture was very well attended and I hope this remains true for the [...]

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Health Care Costs – Part 3, "Why You Are Paying More"

July 19, 2012
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Health Care Costs – Part 3, "Why You Are Paying More"

Malpractice - A Booming Industry?Perhaps authors Frank Sloan, Randall Bovbjerg and Penny Githens capture it best from their book Insuring Medical Malpractice:"If aging Doctor Kildare were to return to medical practice today, having been in suspend...

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Alexa, Maricel, and Marty: Three cellular automata who got on my nerves

July 19, 2012
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I received the following two emails within fifteen minutes of each other. First, from “Alexa Russell,” subject line “An idea for a blog post: The Role, Importance, and Power of Words”: Hi Andrew, I’m a researcher/writer for a resource covering the importance of English proficiency in today’s workplace. I came across your blog andrewgelman.com as [...]

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Help me find the good JSM talks

July 19, 2012
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I’m about to head out for JSM in a couple of weeks. The sheer magnitude of the conference means it is pretty hard to figure out what talks I should attend. One approach I’ve used in the past is to identify people who I know give good talks ...

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Big data is worth nothing without big science

July 19, 2012
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Big data is worth nothing without big science: As with gold or oil, data has no intrinsic value, writes Webtrends CEO Alex Yoder. Big science, which bridges the gap between knowledge and insight, is where the real value is. Read this blog post by Alex ...

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New Kvetch Posted 7/18/12

July 19, 2012
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New Kvetch Posted 7/18/12

New Kvetch Filed under: Uncategorized Tagged: creepy, kvetching, recruiting women in science

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Course at Monash (#1)

July 18, 2012
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Course at Monash (#1)

Here are the slides for the first day of my course at Monash University, Melbourne, in the Special Lectures in Econometrics, with a strong similarity with the slides of my course in Wharton, two years ago. (Be sure to check slide 67! If the update on slideshare works from my flat in Melbourne…) Filed under: [...]

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Sampling Distributions of t When Stopping Intention is Threshold Duration

July 18, 2012
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Sampling Distributions of t When Stopping Intention is Threshold Duration

Consider two groups of data on a metric scale, for which we want to conduct a t test. To compute the p value of t, we need to determine its sampling distribution, which is the relative probability of all possible values of t that would be obtained from...

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Gamification Quantification

July 18, 2012
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Surveys become engaging when they become games, or at least, take on some of the characteristics of games.  This is the argument made by those advocating the gamification of marketing research [http://researchaccess.com/2011/12/market-researc...

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Top Universities Test the Online Appeal of Free

July 18, 2012
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Top Universities Test the Online Appeal of Free: Online courses have been around for years, but now big-name colleges and competing software platforms have entered the field, which is evolving with astonishing speed.

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A closer look at data suggests Johns Hopkins is still the #1 US hospital

July 18, 2012
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A closer look at data suggests Johns Hopkins is still the #1 US hospital

The US News best hospital 2012-20132 rankings are out. The big news is that Johns Hopkins has lost its throne. For 21 consecutive years Hopkins was ranked #1, but this year Mass General Hospital (MGH) took the top spot displacing Hopkins to #2. Howeve...

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The R packages in a data scientist’s toolbox

July 18, 2012
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The R packages in a data scientist’s toolbox

The following from Revolutions: John Myles White, self-described “statistics hacker” and co-author of “Machine Learning for Hackers” was interviewed recently by The Setup. In the interview, he describes his some of his go-to R packages for data science: Most of my work involves programming, so programming languages and their libraries are the bulk of the [...]

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Statistical Simulation

July 18, 2012
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Statistical Simulation

The basics of statistical simulation A statistical simulation often consists of the following steps: Simulate a random sample of size N from a statistical model. Compute a statistic for the sample. Repeat 1 and 2 many times and accumulate the results. Examine the union of the statistics, which approximates the sampling distribution of the statistic [...]

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Johns Hopkins Coursera Statistics Courses

July 18, 2012
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Computing for Data Analysis Data Analysis Mathematical Biostatistics Bootcamp

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The treatment, the intermediate outcome, and the ultimate outcome: Leverage and the financial crisis

July 18, 2012
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Gur Huberman points to an article on the financial crisis by Bethany McLean, who writes: lthough our understanding of what instigated the 2008 global financial crisis remains at best incomplete, there are a few widely agreed upon contributing factors. One of them is a 2004 rule change by the U.S. Securities and Exchange Commission that [...]

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Explanation or Prediction? An Amazing Quote from Phil Schrodt

July 18, 2012
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Explanation or Prediction? An Amazing Quote from Phil Schrodt

I ran across a nice quote from Phil Schrodt on the virtue of explanation over prediction. It starts, "This is utterly, totally and completely self-serving bullshit...", and there is more. I encourage you to share this with others and contribute to the conversation at Explanation or Prediction? An Amazing Quote from Phil Schrodt, which first appeared at carlislerainey.com.For more of my thoughts and ideas, subscribe to my blog (via RSS…

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Simulation in SAS: The slow way or the BY way

July 18, 2012
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Simulation in SAS: The slow way or the BY way

Over the past few years, and especially since I posted my article on eight tips to make your simulation run faster, I have received many emails (often with attached SAS programs) from SAS users who ask for advice about how to speed up their simulation code. For this reason, I [...]

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