New Tutorial on the Gamma Distribution

Figure 1: The impact of varying the shape parameter (alpha) on the gamma distribution.

Although the gamma distribution is widely used in phylogenetics, it remains somewhat of a mystery to many of the students in our annual workshop in applied phylogenetics. Acquiring a basic understanding of the gamma distribution is key to understanding how many widely-used phylogenetic methods work (e.g., MrBayes, BEAST, SIMMAP, BayesTraits). With a bit of help from Brian Moore, I’ve just posted a short tutorial that uses a series of simple R scripts and resulting figures to illustrate how and why the gamma distribution can assume such a wide range of shapes. I hope folks will find this tutorial useful, and encourage you to play around with the scripts I’ve posted to further your understanding of the gamma distribution. Drop me a line if you have any questions.