May 2013

Rmagic, A Handy Interface Bridging Python and R

May 31, 2013 | 0 Comments

Rmagic (http://ipython.org/ipython-doc/dev/config/extensions/rmagic.html) is the ipython extension that utilizes rpy2 in the back-end and provides a convenient interface accessing R from ipython. Compared with the generic use of rpy2, the rmagic extension allows users to exchange objects between ipython and R in a ... [Read more...]

How logistic regression work ?

May 31, 2013 | 0 Comments

Discussing with a non statistician colleague, it seems that the logistic regression is not intuitive; Some basics questions like : - Why don't use the linear model? - What's logistic function? - How can we compute by hand, step by step t... [Read more...]

Generating Nice Looking Tree Diagrams in R

May 31, 2013 | 0 Comments

This function generates nice looking tree diagrams (see sample) below from tree objects (generated by package tree). This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the ... [Read more...]

Snowfall

May 31, 2013 | 0 Comments

Yesterday I had a short post reminding EViews users that their package (versions 7 or 8) will access all of the cores on a multi-core machine. I've been playing around with parallel processing in R on my desktop machine at work over the last few days. It's something I've been meaning to ... [Read more...]

The arteries of the world, in Tweets

May 31, 2013 | 0 Comments

What happens when you plot billions of geotagged Tweets on a map? You can see the arteries of the world. Here's Europe: According to creator Miguel Rios (Engineering Manager, Data Visualization at Twitter), the dots on this chart represent every geotagged Tweet since 2009. The color represents number of tweets in ... [Read more...]

Are parallel computations worth it ?

May 31, 2013 | 0 Comments

Yesterday, Daniel Marcelino published an interesting post on his blog, untitled Parallel Processing: When does it worth ? I was asking myself the same question for a chapter I am currently writing. And I did like his approach, so I tried, on my computer to do the same. I did use ... [Read more...]

Visualizing a One-Way ANOVA using D3.js

May 31, 2013 | 0 Comments

A while ago I was playing around with the JavaScript package D3.js, and I began with this visualization—that I never really finished—of how a one-way ANOVA is calculated. I wanted to make the visualization interactive, and I did integrate some interactive elements. For instance, if you hover ... [Read more...]

Regression regularization example

May 31, 2013 | 0 Comments

Recently I needed a simple example showing when application of regularization in regression is worthwhile. Here is the code I came up with (along with basic application of parallelization of code execution). Assume you have 60 observations and 50 expla... [Read more...]

accurate ABC: comments by Oliver Ratman [guest post]

May 31, 2013 | 0 Comments

Here are comments by Olli following my post: I think we found a general means to obtain accurate ABC in the sense of matching the posterior mean or MAP exactly, and then minimising the KL distance between the true posterior and its ABC approximation subject to this condition. The construction ... [Read more...]

Version control, gitbucket and SourceTree style

May 31, 2013 | 0 Comments

Last time I wrote about version control using Subversion (and its implementation in Eclipse). I still haven’t given up on it, but since I’m using a private repository, sharing code has been a bit tedious. I was introduced to git a while ago, but somehow decided to go ... [Read more...]

”How to draw the line” with ggplot2

May 30, 2013 | 0 Comments

In a recent tutorial in the eLife journal, Huang, Rattner, Liu & Nathans suggested that researchers who draw scatterplots should start providing not one but three regression lines. I quote, Plotting both regression lines gives a fuller picture of the data, and comparing their slopes provides a simple graphical assessment of ... [Read more...]

my 1st post for the Guardian Australia

May 30, 2013 | 0 Comments

I’ll be contributing a piece about once a week for the Guardian Australia, under a part of the web site we’re calling The Swing. The set of graphs from my 1st effort were rendered in-line and rather low-res. Bigger, full res versions appear below; click on the in-line ... [Read more...]

Uncovering the Unreliable Friend Distribution

May 30, 2013 | 0 Comments

Head down to your local hardware store and pick up a smoke detector. Pop off the cover and look inside. You’ll see a label that mentions Americium 241, a radioactive isotope. Put on your HEV suit, grab a pair of tweezers and a fine-tipped pen, and remove the 0.3 millionths of ... [Read more...]

Scenario analysis for option strategies.

May 30, 2013 | 0 Comments

Introduction to the project I am working on at the moment. It is more a playground for option strategies than "project" at this stage. The idea is to develop accurate scenario analysis on portfolio, which is based on a single underlying. In the past I ...
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If…then in Japan

May 30, 2013 | 0 Comments

If Japan starts to spiral out of control, then what do they do? A spiral would be a sudden move higher in JGB rates with a simultaneous crash in the Japanese Yen. Their response would be to try to slow the positive feedback loop through external interv...
[Read more...]

Ryan Sheftel: "R on the Trading Desk"

May 30, 2013 | 0 Comments

by Joseph Rickert In a post last week, I offered some first impressions about R/Finance 2013. Apparently, I was way off in estimating that 30% of the attendees were academics. The R/Finance organizers were quick to point out that percentage of academics attending the conference has been a constant 10% over ... [Read more...]

Are the Current Criteria for Empirically Supported Treatments Too Lenient?

May 30, 2013 | 0 Comments

The practice of classifying treatments as empirically supported (ESTs) has been widely debated for a long time. Recently Jessica Nasser published an article in the Journal of Contemporary Psychotherapy named “Empirically Supported Treatments and Efficacy Trials: What Steps Do We Still Need to Take?”. In the article the author raises ... [Read more...]

Couch, apis and all that

May 30, 2013 | 0 Comments

It is getting easier to get data directly into R from the web. Often R packages that retrieve data from the web return useful R data structures like a data.frame or plot. This is a good thing of course to make things user friendly. However, what if you want ... [Read more...]

Are Fox News Polls Biased?

May 29, 2013 | 0 Comments

Especially after the outcome of the mid-term election, I think there is a common contention among some groups that there is something wonky about Fox News when it comes to reporting polls relative to President Obama and the Democratic Party in general.... [Read more...]
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