I am comparing estimates from subject-specific GLMMs and population-average GEE models as part of a publication I am working on. As part of this, I want to visualize predictions of each type of model including 95% confidence bands. First I … Continue reading →
Around Christmas time I presented my first impressions of Kruschke’s Doing Bayesian Data Analysis. This is a very nice book but one of its drawbacks was that part of the code used BUGS, which left mac users like me stuck. … Continue reading →
Those of you following my occasional updates here know that I have previously posted code for graphing Twitter friend/follower networks using R (post #1. post #2). Kai Heinrich was kind enough to send me some updated code for doing so using a newer version of the extremely useful twitteR package. His very crisp, yet thoroughly
I received an email from one of my students expressing deep frustation with a seemingly simple problem. He had a factor containing names of potato lines and wanted to set some levels to NA. Using simple letters as example names … Continue reading →
I honestly have no book on R programming. In fact I have not a single book on programming at all (my coding proves that ;x). I am pretty sure that I am gonna order (just did!) that book. You can get a look of Matloff’s text here (= pdf for ya)
When working in research projects I tend to fit several, sometimes quite a few, alternative models. This model fitting is informed by theoretical considerations (e.g. quantitative genetics, experimental design we used, our understanding of the process under study, etc.) but … Continue reading →
This is simple example code to display side-by-side lattice plots or ggplot2 plots, using the mtcars dataset that comes with any R installation. We will display a scatterplot of miles per US gallon (mpg) on car weight (wt) next to … Continue reading →
We were talking with one of my colleagues about doing some text analysis—that, by the way, I have never done before—for which the first issue is to get text in R. Not any text, but files that can be accessed … Continue reading →
There are times when we need to write a function that makes changes to a generic data frame that is passed as an argument. Let’s say, for example, that we want to write a function that converts to factor any … Continue reading →
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
