Blog Archives

Please send all comments to /dev/ripley

July 10, 2013
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Please send all comments to /dev/ripley

Trey Causey asks, Has R-help gotten meaner over time?: I began by using Scrapy to download all the e-mails sent to R-help between April 1997 (the earliest available archive) and December 2012. . . . We each read 500 messages and coded them in the following categories: -2 Negative and unhelpful -1 Negative but helpful The post Please...

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R sucks

June 29, 2013
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I was trying to make some new graphs using 5-year-old R code and I got all these problems because I was reading in files with variable names such as “co.fipsid” and now R is automatically changing them to “co_fipsid”. Or maybe the names had underbars all along, and the old R had changed them into The post R...

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Are Green Number Runners More Likely to Bail?

June 22, 2013
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Are Green Number Runners More Likely to Bail?

Comrades Marathon runners are awarded a permanent green race number once they have completed 10 journeys between Durban and Pietermaritzburg. For many runners, once they have completed the race a few times, achieving a green number becomes a possibility. And once the idea takes hold, it can become something of a compulsion. I can testify

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Job openings at conservative political analytics firm!

June 21, 2013
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Job openings at conservative political analytics firm!

After posting that announcement about Civis Analytics, I wrote, “If a reconstituted Romney Analytics team is hiring, let me know and I’ll post that ad too.” Adam Schaeffer obliged: Not sure about Romney’s team, but Evolving Strategies is looking for sharp folks who lean right: Evolving Strategies is a political communications research firm specializing in The post Job...

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The Green Number Effect

June 18, 2013
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The Green Number Effect

Following up on a suggestion from my previous post, here are the statistics for medal count versus age. Every point on the plot is the number (see colour legend on right) of athletes who have achieved a given number of medals by a particular age. There is clear evidence of a Green Number Effect: many

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Job opening! Come work with us!

June 18, 2013
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Postdoctoral position in statistical modeling of social networks A full-time postdoctoral position is available beginning Fall 2014 in the research group of Tian Zheng and Andrew Gelman working on statistical analysis and modeling of social network data, in close cooperation with our experimental collaborators. Four key papers of this project so far are: http://www.stat.columbia.edu/~gelman/research/published/overdisp_final.pdf http://nersp.osg.ufl.edu/~ufruss/documents/mccormick_salganik_zheng10.pdf The post Job...

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Medal Allocations at the Comrades Marathon

June 9, 2013
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Medal Allocations at the Comrades Marathon

Following up on my previous post regarding attrition rates at Comrades Marathon 2013, here are the statistics I have gathered for medal allocations. There is some interesting history behind the Comrades Marathon medals. For reference, the medals are allocated as follows: Gold medals to the first ten finishers in the men’s race and the ladies’ race;

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Robust logistic regression

June 7, 2013
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Corey Yanofsky writes: In your work, you’ve robustificated logistic regression by having the logit function saturate at, e.g., 0.01 and 0.99, instead of 0 and 1. Do you have any thoughts on a sensible setting for the saturation values? My intuition suggests that it has something to do with proportion of outliers expected in the The post Robust...

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Comrades Marathon Attrition Rate

June 7, 2013
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Comrades Marathon Attrition Rate

It is a bit of a mission to get the complete data set for this year’s Comrades Marathon. The full results are easily accessible, but come as an HTML file. Embedded in this file are links to the splits for individual athletes. So with a bit of scripting wizardry it is also possible to download

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Analysis of Cable Morning Trade Strategy

May 29, 2013
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Analysis of Cable Morning Trade Strategy

A couple of years ago I implemented an automated trading algorithm for a strategy called the “Cable Morning Trade”. The basis of the strategy is the range of GBPUSD during the interval 05:00 to 09:00 London time. Two buy stop orders are placed 5 points above the highest high for this period; two sell stop

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