After my post on making dotplots with concise code using plyr and ggplot, I got an email from my dad who practices immigration law and runs a website with a variety of immigration resources and tools. He pointed out that the … Continue reading →
Monthly Archives: March 2012
Visualization series: Insight from Cleveland and Tufte on plotting numeric data by groups
Spurious Regression illustrated
Spurious Regression problem dates back to Yule (1926): “Why Do We Sometimes Get Nonsense Correlations between Time-series?”. Lets see what is the problem, and how can we fix it. I am using Morgan Stanley (MS) symbol for illustration, pre-crisis time … Continue reading →
Setting the Default RNG Seed in R
How to set the default seed for the RNG behind the runif(), sample() and other command? Well, there are several ways doing that (like setting .Random.seed directly), but as the documentation states, set.seed() is the recommended way to specify seeds.
> ?set.seed
> set.seed(0)
> runif(1,0,1)
0.8966972
> set.seed(0)
> runif(1,0,1)
0.8966972
> set.seed(0)
> sample(1:10, 10)
9 3 10 5 ...
My Pocket Change
I'm playing around with some personal data collection, and using some cloud computing to visualize it. Following the directions in this blog post, I've written an R function which visualizes data it draws from a Google Docs spreadsheet, and uploaded it...
Capturing Tick Data via C#, Interactive Brokers, and MySQL
Interactive Brokers is a discount brokerage that provides a good API for programatically accessing their platform. The purpose of this post is to create an application that will capture tick level data and save that data into a database for futur...
Gastwirth’s location estimator
The problem of outliers – data points that are substantially inconsistent with the majority of the other points in a dataset – arises frequently in the analysis of numerical data. The practical importance of outliers lies in the fact that even a few of these points can badly distort the results of an otherwise reasonable data analysis. This outlier-sensitivity...
R versus Stata Redux
I've used both R and Stata for a long time, but these days I use Stata much more frequently than R. While R is useful for some kinds of graphics (especially three-dimensional graphics) and some statistical procedures (for example, finite mixture models...
NIT: Fatty acids study in R – Part 002
> library(chemometrics)> fatmsc_nipals<-nipals(fat_msc,a=10,it=160)> CPs<-seq(1,10,by=1)> matplot(CPs,t(fatmsc_nipals$T),lty=1,pch=21, + xlab="PC_number",ylab="Explained_Var")In the 2D plot, we can see that with 3 or 4 principal...
The German DIN33430 – Analysis of acceptance with R
The german DIN33430 defines quality standards that must be met in “job-related proficiency assessments”, the qualifications of the responsible parties involved, as well as the creation, execution and evaluation of such assessments. Licensed persons are published on a website (german). … Weiterlesen →
New data visualization features in ggplot2 update
Hadley Wickham has just released an update to the ggplot2 graphics package for R. Version 0.9.0 significantly speeds up the process of rendering graphics, and the documentation is much improved (including the addition of many new examples). This update also adds a bunch of new features, which are documented in this 40-page "changes and additions" guide. Here's a sampling...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
