The Second Coming

June 18, 2009
By

Pew Research has found that 79% of Americans believe in The Second Coming of Jesus. What worries me more is not that 4 out of 5 Americans believe in The Second Coming, but that 1 out of 5 believes it will happen in their lifetime. It seems inevitable that such a belief will grossly warp

Read more »

The Second Coming

June 18, 2009
By

Pew Research has found that 79% of Americans believe in The Second Coming of Jesus. What worries me more is not that 4 out of 5 Americans believe in The Second Coming, but that 1 out of 5 believes it will happen in their lifetime. It seems inevitable t...

Read more »

Influence.ME: don’t specify the intercept

June 18, 2009
By

Just recently, I was contacted by a researcher who wanted to use influence.ME to obtain model estimates from which iteratively some data was deleted. In his case, observations were nested within an area, but there were very unequal numbers of ...

Read more »

Hierarchical Clustering in R

June 16, 2009
By

Hierarchical clustering is a technique for grouping samples/data points into categories and subcategories based on a similarity measure. Being the powerful statistical package it is, R has several routines for doing hierarchical clustering. The basic command for doing HC is hclust(d, method = "complete", members=NULL) Nearly all clustering approaches use a concept of distance. Data points

Read more »

Not Just Normal… Gaussian

June 16, 2009
By
Not Just Normal… Gaussian

Dave, over at The Revolutions Blog, posted about the big ‘ol list of graphs created with R that are over at Wikimedia Commons. As I was scrolling through the list I recognized the standard normal distribution from the Wikipedia article on the same topic. Below is the fairly simple source code with lots of comments. Here’s

Read more »

NYT: In Simulation Work, the Demand Is Real

June 16, 2009
By

The New York Times published this interesting article on how the ability to design and perform computer simulations is a highly marketable skill for careers across many disciplines.In methodology development we use simulation nearly every day. We've developed our own specialized genetic data simulation software, genomeSIMLA, that's freely available here by request for PC, Mac, and Linux.But if...

Read more »

One outlier and you’re out: Influential data and racial prejudice

June 16, 2009
By
One outlier and you’re out: Influential data and racial prejudice

Currently preparing a presentation on analyzing influential data in mixed effects models myself, my eye fell on an article in which important claims on racial prejudice were refuted. An important aspect of the criticism on existing work, is that in ...

Read more »

R tips: Determine if function is called from specific package

June 16, 2009
By
R tips: Determine if function is called from specific package

I like the "multicore" library for a particular task. I can easily write a combination of if(require("multicore",...)) that means that my function will automatically use the parallel mclapply() instead of lapply() where it is available. Which is grand 99% of the time, except when my function is called from mclapply() (or one of the lower level functions)...

Read more »

R tips: Determine if function is called from specific package

June 16, 2009
By
R tips: Determine if function is called from specific package

I like the "multicore" library for a particular task. I can easily write a combination of if(require("multicore",...)) that means that my function will automatically use the parallel mclapply() instead of lapply() where it is available. Which is grand 99% of the time, except when my function is called from mclapply() (or one of the lower level functions)...

Read more »

Who wants school vouchers? Rich whites and poor nonwhites

June 15, 2009
By

As part of our Red State, Blue State research, we developed statistical tools for estimating public opinion among subsets of the population. Recently Yu-Sung Su, Yair Ghitza, and I applied these methods to see where school vouchers are more or...

Read more »

Geography and Data

June 15, 2009
By

The Economist recently ran a fascinating article about the emergence of geographical databases and their uses for presenting and analyzing data.All this has made it much easier to create maps that explain—at a glance—something that might otherwise require pages of tables or verbiage. “A percentage or a table is still abstract for people,” says Dan Newman of MAPLight.org,...

Read more »

Side by side analyses in Stata, SPSS, SAS, and R

June 15, 2009
By

I've linked to UCLA's stat computing resources once before on a previous post about choosing the right analysis for the questions your asking and the data types you have. Here's another section of the same website that has code to run an identical analysis in all of these statistical packages, with examples to walk through (as they note...

Read more »

Replacing 0 with NA – an evergreen from the list

June 15, 2009
By
Replacing 0 with NA – an evergreen from the list

This thread from the R-help list describe an evergreen tip that, at least once, is proved useful in R practice.

Read more »

Example 7.2: Simulate data from a logistic regression

June 13, 2009
By
Example 7.2: Simulate data from a logistic regression

It might be useful to be able to simulate data from a logistic regression (section 4.1.1). Our process is to generate the linear predictor, then apply the inverse link, and finally draw from a distribution with this parameter. This approach is useful in that it can easily be applied to other generalized linear models. In this...

Read more »

Example 7.1: Create a Fibonacci sequence

June 12, 2009
By
Example 7.1: Create a Fibonacci sequence

The Fibonacci numbers have many mathematical relationships and have been discovered repeatedly in nature. They are constructed as the sum of the previous two values, initialized with the values 1 and 1.A pdf of this example is available here.SASIn SAS, we use the lag function (section 1.4.17,...

Read more »

R tips: Installing Rmpi on Fedora Linux

June 12, 2009
By
R tips: Installing Rmpi on Fedora Linux

Somebody on the R-help mailing list asked how to get Rmpi working on his Fedora Linux machine so he could do high-performance computing on a cluster of machines (or a single multicore machine) using the R statistical computing and analysis platform. Since it is unusually painful to get working, I might as well copy the instructions...

Read more »

R tips: Installing Rmpi on Fedora Linux

June 12, 2009
By
R tips: Installing Rmpi on Fedora Linux

Somebody on the R-help mailing list asked how to get Rmpi working on his Fedora Linux machine so he could do high-performance computing on a cluster of machines (or a single multicore machine) using the R statistical computing and analysis platform. Since it is unusually painful to get working, I might as well copy the instructions...

Read more »

Simulation of Burning Fire in R

June 11, 2009
By
Simulation of Burning Fire in R

inlin Yan posted a cool (hot?) simulation of burning fire with R in the COS forum yesterday, which was indeed a warm welcome. I’m not sure whether our forum members will be scared by the “fire” under the title “Welcome to COS Forum”. The fire was mainly created by the function image() with

Read more »

Creating Tag Cloud Using R and Flash / JavaScript (SWFObject)

June 10, 2009
By
Creating Tag Cloud Using R and Flash / JavaScript (SWFObject)

ag cloud is a bunch of words drawn in a graph with their sizes proportional to their frequency; it’s widely used in blogs to visualize tags. We can observe important words quickly from a tag cloud, as they often appear in large fontsize. Tony N. Brown asked how to “graphically represent frequency of words in

Read more »

Hack-at-it 2009

June 9, 2009
By
Hack-at-it 2009

The annual GGobi hack-at-it was held June 5-7 in Ames Iowa. The main directions of work areDevelopment of a new canvas for R supporting interactive and dynamic graphics. Michael is leading the effort on this. Higher level routines for supporting brushi...

Read more »

Hack-at-it 2009

June 9, 2009
By
Hack-at-it 2009

The annual GGobi hack-at-it was held June 5-7 in Ames Iowa. The main directions of work areDevelopment of a new canvas for R supporting interactive and dynamic graphics. Michael is leading the effort on this. Higher level routines for supporting brushi...

Read more »

Data Mashups in R from O’Reilly

June 9, 2009
By
Data Mashups in R from O’Reilly

O’Reilly has published Data Mashups in R as a $4.99 PDF download in their Short Cut series. In 27 pages it takes you through an example of how to combine foreclosure information with maps and geographical information...

Read more »

Data Mashups in R from O’Reilly

June 9, 2009
By
Data Mashups in R from O’Reilly

O’Reilly has published Data Mashups in R as a $4.99 PDF download in their Short Cut series. In 27 pages it takes you through an example of how to combine foreclosure information with maps and geographical information...

Read more »

Two plot with a common legend – base graphics

June 6, 2009
By
Two plot with a common legend – base graphics

If you need to share a common legend between two graphs using the ggplot2 package/paradigm take a look at this post from the Learning R blog.The code below solves the same task using the R base graphics.png( "2plot1legend.png", width = 480, height = 68...

Read more »

Learning R for Researchers in Psychology

June 6, 2009
By
Learning R for Researchers in Psychology

R is a powerful environment for statistical computing. Here is a selective list of resources on R with an emphasis on resources useful for researchers in psychology.Psychology specific R resourcesR Notes for Experimental PsychologyWilliam Revelle's Psy...

Read more »

Introductory statistics with R

June 5, 2009
By

I know that a lot of you are scrambling to spend your training grant money by next week. If you think you'll ever need to use R, I strongly recommend buying this book: Introductory Statistics with R, by Peter Dalgaard ($48, Amazon). I picked this up a while back and read through most of it in a...

Read more »

Elementary Statistics with R

June 5, 2009
By
Elementary Statistics with R

Ever wonder how to finish your statistics homework real fast? Or you just want a quick way to verify your tedious calculations in your statistics class assignment. We provide an answer here by solving statistics exercises with R. read more

Read more »

Getting started with R (for german speakers)

June 5, 2009
By
Getting started with R (for german speakers)

Just a little note for german speaking R beginners: There is an introductory course in R (german) available online on the website of the department of methodology and evaluation research at the University of Jena. Dr. Ivailo Partchev holds a seven sess...

Read more »

Twitter from R… Sure, why not!

June 4, 2009
By
Twitter from R… Sure, why not!

So I have started following the #RStats tag in twitter. Prior to a week ago I had never Twitterbated so I thought I would give it a go since I am not one to shy away from new technology… much. I think of Twitter like a call in radio show where I get to cut

Read more »