Articles by Corey Chivers

How likely is the NSA PRISM program to catch a terrorist?

June 6, 2013 | Corey Chivers

Recent revelations about PRISM, the NSA’s massive program of surveillance of civilian communications have caused quite a stir. And rightfully so, as it appears that the agency has been granted warrantless direct access to just about any form of digital communication engaged in by American citizens, and that their ... [Read more...]

What is probabilistic truth?

May 18, 2013 | Corey Chivers

I am currently working on a validation metric for binary prediction models. That is, models which make predictions about outcomes that can take on either of two possible states (eg Dead/not dead, heads/tails, cat in picture/no cat in picture, etc.) The most commonly used metric for this ... [Read more...]


May 7, 2013 | Corey Chivers

Reblogged from Zero to R Hero: Canadian Aquatic Invasive Species Networks Annual General Meeting in Kananaskis, Alberta. May 03, 3:25-5:30. This 2-hour workshop will focus on how and why we do numerical simulation in R. Time permitting, we will also look at how to build and fit likelihood based statistical models. ... [Read more...]

A quick guide to non-transitive Grime Dice

April 7, 2013 | Corey Chivers

A very special package that I am rather excited about arrived in the mail recently. The package contained a set of 6-sided dice. These dice, however, don’t have the standard numbers one to six on their faces. Instead, they have assorted numbers between zero and nine. Here’s the ... [Read more...]

Open Data Exchange 2013, April 6. Montreal

March 29, 2013 | Corey Chivers

UPDATE: The day was great! There are many people doing really amazing things with open data and it was amazing to meet them. Here are my slides from the panel talk. Next Saturday, I’ll be sitting on a panel discussing future avenues for open data at ODX13. From the ... [Read more...]

Introduction to Simulation using R

March 23, 2013 | Corey Chivers

We had a great turnout yesterday for our Zero to R Hero workshop at the Quebec Centre for Biodiversity Science. We went from the absolute basics of the command line, to the intricacies of importing data, and finally we had a look at plotting using ggplot2. We didn’t have ... [Read more...]

The Gambling Machine Puzzle

March 9, 2013 | Corey Chivers

This puzzle came up in the New York Times Number Play blog. It goes like this: An entrepreneur has devised a gambling machine that chooses two independent random variables x and y that are uniformly and independently distributed between 0 and 100. He plans to tell any customer the value of x ... [Read more...]

Montreal R User group meetup at Wajam

January 21, 2013 | Corey Chivers

This Thursday (Jan 24th), 5:30pm, the good folks at Wajam are hosting a meetup of the Montreal R User Group. The event will be at Bolidea at 4115 St Laurent, Montréal, QC. Be sure to RSVP. From Benjamin Rollert: This is an opportunity for people interested in R to hang ... [Read more...]

Dark matter top 10, but an hour too late

December 16, 2012 | Corey Chivers

Well, that’s embarrassing. A little tweak to my dark matter model resulted in a leaderboard score in the top 10. The only problem is that the contest closed about an hour ago. I ran this final prediction earlier today but then simply forgot to go back to it and submit!! ... [Read more...]

Simulating weak gravitational lensing

November 24, 2012 | Corey Chivers

In the search for dark matter, I have been having mixed success. It seems that locating DM in single halo skies is a fairly straightforward problem. However, when there are more than one halo, things get quite a bit trickier. As I have advocated many times before, including here and ... [Read more...]

IPython vs RStudio+knitr

November 21, 2012 | Corey Chivers

At a meeting last night with some collaborators at the Vélobstacles project, I was excitedly told about the magic of IPython and it’s notebook functionality for reproducible research. This sounds familiar, I thought to myself. Using a literate programming approach to integrate computation with the communication of methodology ... [Read more...]

What does R do? Bring people together, of course!

November 15, 2012 | Corey Chivers

Last night we had a great meet up of the Montreal R User Group. I got things started with a little presentation asking the question “What does R do?” (slides). I made the presentation using Montreal R User Group member Ramnath Vaidyanathan‘s Slidify package. Slidify allows you to generate ... [Read more...]

Montreal R User Group meetup Nov. 14th

October 29, 2012 | Corey Chivers

After a bit of a summer lull, the Montreal R User Group is meeting up again! We’re trying out a new venue this time. Notman House is the home of the web in Montreal. They hold hackathons and other tech user group meetups, and they are all around great ... [Read more...]

Dark matter benchmarks: All over the map

October 14, 2012 | Corey Chivers

The three benchmark algorithms for predicting the location of dark matter halos are, for the most part, all over the map. Most of the test skies look something like this: There are, however, some skies with rather strong halo signals that get a decent amount of agreement: The Lenstool MLE ... [Read more...]
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