October 2011

Two seasonal investors – R snippet

October 24, 2011 | enguyen

In “A tale of 2 Seasonal Investors“, the Big Picture discusses the simple idea of comparing two simple investment approaches: being exposed to the market 6 months every year (from November to April), as opposed to investing in the other 6 months of every year (from May to October). Going back 50 years in ... [Read more...]

NYT on Big Data and R

October 24, 2011 | David Smith

In the New York Times' "Bits" blog today, Quentin Hardy offers recollections on Big Data talks at the recent Web 2.0 Summit. He begins with a definition of Big Data: Big Data is really about ... the benefits we will gain by cleverly sifting through it to find and exploit new patterns ... [Read more...]

Show me your WAR face!

October 24, 2011 | hawkhandler

Below is a chart of the top 20 offensive players based on FanGraphs WAR for the 2011 season.  The various features and their corresponding metric are clear in the image. I’ve also included the leader and last place for each … Continue reading → [Read more...]

XLConnect 0.1-7

October 24, 2011 | Mirai Solutions

Mirai Solutions GmbH (http://www.mirai-solutions.com) is pleased to announce the availability of XLConnect 0.1-7. This release includes a number of improvements and new features: Performance improvements when writing large xlsx files New workbook data extraction & replacement operators [, [ [Read more...]

Parameter vs. Observation Dimension?

October 24, 2011 | BioStatMatt

Bill Bolstad's response to Xi'an's review of his book Understanding Computational Bayesian Statistics included the following comment, which I found interesting: Frequentist p-values are constructed in the parameter dimension using a probability distribution defined only in the observation dimension. Bayesian credible intervals are constructed in the parameter dimension using a ... [Read more...]

How to compute portfolio returns badly

October 24, 2011 | Pat

For those who naturally compute portfolio returns correctly here are some lessons in how to do it wrong. The data Random portfolios were generated from constituents of the S&P 500 with constraints: long-only exactly 20 assets in the portfolio no more than 10% weight for any asset (just for fun) the sum ... [Read more...]

Machine Learning Ex4 – Logistic Regression

October 24, 2011 | R on Guangchuang Yu

Exercise 4 required implementing Logistic Regression using Newton's Method. The dataset in use is 80 students and their grades of 2 exams, 40 students were admitted to college and the other 40 students were not. We need to implement a binary classification model to estimates college admission based on the student's scores on these two ... [Read more...]

Isarithmic Maps of Public Opinion Data

October 24, 2011 | d sparks

As a follow-up to my isarithmic maps of county electoral data, I have attempted to experiment with extending the technique in two ways. First, where the electoral maps are based on data aggregated to the county level, I have sought to generalize the method to accept individual responses for which ... [Read more...]

Normality tests don’t do what you think they do

October 23, 2011 | Ian

Last week a question came up on Stack Overflow about determining whether a variable is distributed normally. Some of the answers reminded me of a common and pervasive misconception about how to apply tests against normality. I felt the topic was general enough to reproduce my comments here (with minor ... [Read more...]

Winning the Netflix Prize: A Summary

October 23, 2011 | Edwin Chen

How was the Netflix Prize won? I went through a lot of the Netflix Prize papers a couple years ago, so I’ll try to give an overview of the techniques that went into the winning solution here. Normalization of Global Effects Suppose Alice rates Inception 4 stars. We can think ... [Read more...]

Using Sweave with XeLaTeX

October 23, 2011 | mages

Using R with LaTeX via Sweave is a great way to create reproducible output. However, using specific fonts, e.g. your corporate fonts, can be painful with pdflatex. Over the last few weeks I have fallen in love with the TeX formatXeLaTeX and its XeTeX e...
[Read more...]
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