You've probably heard of the Birthday Paradox: it only takes a small gathering of people before it's quite likely that two of them share the same birthday. You can solve the problem analytically or with simulation, but usually in either case simplifying assumptions are made (no-one born on February 29, for ... [Read more...]

Exploring whether regression coefficients differ between groups is an important part of applied econometric research, and particularly for research with a policy based objective. For example, a government in a developing country may decide to introduce free school lunches in an effort to improve childhood health. However, if this treatment ... [Read more...]

Prime is the core of number theory. Here is an introduction of prime number on Wikipedia. I could only understand roughly half of it. Now, let’s look at the seventh problem of Project Euler, which is another about prime number.  By listing the first six prime numbers: 2, 3, … Continue reading → [Read more...]

[Read more...]

This post is from my new book Forecasting: principles and practice, available freely online at OTexts.com/fpp/. A non-seasonal ARIMA model can be written as (1)   or equivalently as (2)   where is the backshift operator, and is the mean of . R uses the parametrization of equation (2). Thus, the inclusion of a ... [Read more...]

Revolution Analytics is proud to announce the latest update to our enhanced, production-grade distribution of R, Revolution R Enterprise. This update expands the range of supported computation platforms, adds new Big Data predictive models, and updates to the latest stable release of open source R (2.14.2), which improves performance of the ... [Read more...]

[Read more...]

Today I want to examine the performance of stocks in the S&P 500 grouped into Quantiles based on one year historical Volatility. The idea is very simple: each week we will form Volatility Quantiles portfolios by grouping stocks in the S&P 500 into Quantiles using one year historical Volatility. Next ... [Read more...]

Following the announcement of the US Government Big Data Initiative, I was asked to write a small article about applications of R in government. The article has just appeared in Government Security News (and I believe will appear in their daily newsletter tomorrow). In the article, I highlighted several R ... [Read more...]

In our pre-conference workshop, Brian Peterson and I worked with the EDHEC hedge fund indexes as a way to demonstrate how to use PortfolioAnalytics within the context of long-term allocation problems. Although they are not investible, these indexes are probably more representative than most given that they are, in fact, ... [Read more...]

Many of you have heard about RStudio’s latest release and it’s new R Markdown feature. Today, I’d like to announce the markdown package for R, a tool for converting Markdown documents to HTML, created in collaboration with RStudio. It... [Read more...]

by Yanchang Zhao, RDataMining.com There are some nice slides and R code examples on Data Mining and Exploration at http://www.inf.ed.ac.uk/teaching/courses/dme/, which are listed below. PDF Slides: - Overview of Data Mining http://www.inf.ed.ac.uk/teaching/courses/dme/2012/slides/... [Read more...]

In this video tutorial, it will show you how to make R analysis Modules just like MS Excel Templates using the Building Derivative Calculator app as study case. Let’s say we wanted to know the derivative of tan(x^2 + 3), commonly, we will use th... [Read more...]

ggplot2 improves the graphics drawn with R. A (very) short adaptation time is needed to find how to make graphs equivalent to the ones of graphics. For example, to draw the curve of a function, there is no function similar to curve(). You have to use qplot() by setting the ... [Read more...]

[Read more...]

Here is the code that fixed up the World Bank data export for use in Tableau. The databank spits out everything in an untidy format for grouping and aggregating. The reshape2 and plyr packages  make it easy to manipulate the whole set … Continue reading → [Read more...]

It’s midnight officially. Let me solve the sixth problem before bed. This is a quick one. The sum of the squares of the first ten natural numbers is, 12 + 22 + … + 102 = 385. The square of … Continue reading → [Read more...]

I wanted to get these releases out the door before the useR conference, especially since I’m giving a tutorial on Rook! There were two bugs found in Rook, not by me, but by users! This is a fantastic step in the right direction as it’s an ... [Read more...]

[Read more...]

Patrick Burns, author of the excellent R Inferno, gave a presentation about R at the Cambridge R User Group this week. (Revolution Analytics is a proud sponsor of CambR.) I wasn't at the presentation myself, but Pat always gives a great talk, and he's generously provided his slides with copious ... [Read more...]