As I mentioned in a recent post, I’ve just received a copy of Advanced Markov Chain Monte Carlo Methods. Chapter 1.4 in the book (very quickly) covers random variable generation. Inverse CDF Method A standard algorithm for generating random numbers is the inverse cdf method. The continuous version of the algorithm is as follows: 1. 
An obvious omission in my previous post on Great-circle distance calculations in R was a lack of discussion on the computational efficiency of the various methods, and in particular comparing different implementations of the same method. One of the comments … Continue reading →
Recently I found myself needing to calculate the distance between a large number of longitude and latitude locations. As it turns out, because the earth is a three-dimensional object, you cannot simply pretend that you are in Flatland, albeit some … Continue reading →
One of the current best tools in the machine learning toolbox is the 1930s statistical technique called logistic regression. We explain how to add professional quality logistic regression to your analytic repertoire and describe a bit beyond that. A statistical analyst working on data tends to deliberately start simple move cautiously to more complicated methods. Related posts:
I have made several updates to RClimate tools for do-it-yourself climate scientists. The downloadable monthly climate trends file (link to csv file) now includes the 5 major global land-ocean temperature anomaly time series (GISS, HAD, NOAA, RS...
InfoChimps.com is mainly known as a clearinghouse for finding large data sets, for free or for sale. But they have also released (in beta, at least) an API that lets you find some pretty useful information on-demand. Normally, you'd have you use RESTful calls to access the API, but now Drew Conway has created an R package (and released...
In logistic regression, when the outcome has low (or high) prevalence, or when there are several interacted categorical predictors, it can happen that for some combination of the predictors, all the observations have the same event status. A similar e...
Spending the day churning through large data set or doing some heavy-duty number crunching? What is one to do while the computer is running in overdrive? We’ll, for one, you could get a steaming cup of joe and write a … Continue reading →
Please note - I’ve spotted a problem with the approach taken in this post – it seems to underestimate power in certain circumstances. I’ll post again with a correction or a more full explanation when I’ve sorted it. So, I posted an answer on cross validation regarding logistic regression. I thought I’d post it 
A few months ago I showed you how to syntax-highlight R code using Github Gists for displaying R code on your blog or other online medium. The idea's really simple if you use blogger - head over to gist.github.com, paste in your R code, create a public "gist", hit "embed", then copy the javascript onto your blog. However, if...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
