I only visited a few JSM sessions today, as I’ve been focused on preparing for my own talk tomorrow morning. However, I went to several talks in a row which all had a common problem that made me cringe: graphics … Continue reading →

In a political party, there are as many cells as there are members and each member belongs to at least one cell. Each cell has five members and an arbitrary pair of cells only shares one member. How many members are there in this political party? Back to the mathematical puzzles of Le Monde (science

Standard nonlinear regression assumes homoscedastic data, that is, all response values are distributed normally. In case of heteroscedastic data (i.e. when the variance is dependent on the magnitude of the data), weighting the fit is essential. In nls (or nlsLM of the minpack.lm package), weighting can be conducted by two different methods: 1) by supplying

This post presents the video of a talk that I presented in July 2012 at Melbourne R Users on using knitr, R Markdown, and R Studio to perform reproducible analysis. I also provide links to a github repository where the R markdown examples can be examin...

It’s all very well publishing a research paper that describes the method for, and results of, analysing a dataset in a particular way, or a news story that contains a visualisation of an open dataset, but how can you do so transparently and reproducibly? Wouldn’t it be handy if you could “View Source” on the

Chaos. Hectic, seemingly unpredictable, complex dynamics. In a word: fun. I usually stick to the warm and fuzzy world of stochasticity and probability distributions, but this post will be (almost) entirely devoid of randomness. While chaotic dynamics are entirely deterministic, their sensitivity to initial conditions can trick the observer into seeing iid. In ecology, chaotic