Correcting for confounded variables with GLMs General (and generalized) linear models can be useful for analyzing field data, where sampling is often distributed unevenly across different environmental gradients or treatment groups. They help us corre... [Read more...]

Universal inference in R When we perform a statistical test we’d like to have confidence what the Type I error rate is what we say it is (rate of false positive findings). Often scientists choose a rate (AKA ‘alpha’) of 0.05 for rejecting the nu... [Read more...]

Time sinks for data wrangling Estimating the time it will take to complete a project is an important part of being a successful PhD student, researcher or consultant. A major time sink on many analytical projects is data wrangling. Often the wranglin... [Read more...]

How much has the data informed your isotope mixing model? The contributions of different food sources to animal diets is often a mystery. Isotopes provide a means to estimate those contributions, because different food sources often have different iso... [Read more...]

A case against pipes in R and what to do instead Pipes (%__%) are great for improving readibility of lengthy data processing scripts, but I’m beggining to learn they have some weaknesses when it comes to large and complex data processing. We are ... [Read more...]

Spatial predictions with GAMs and rasters One powerful use of GAMs is for interpolating to unsampled locations. We can combine GAMs with raster package to conveniently predict a GAM model to places we have not got data. Simulate some spatial data We... [Read more...]

Three ways to calculate distances in R Calculating a distance on a map sounds straightforward, but it can be confusing how many different ways there are to do this in R. This complexity arises because there are different ways of defining ‘distance?... [Read more...]

Using R and power analysis to inform experimental design A collaborator once asked me: “can you do that thing where you take a little bit of data and model it up to make lots more data?” Does it sound suspicious to fake a lot of data from a littl... [Read more...]

Make a map of your study site with tmap I’m loving the tmap package right now. Here’s why. And we’ll look at how to make a clean map of a study site as we go. We’ll use the data from our study of pollution and coral ... [Read more...]

Informing priors for a time-series models to detect declines in tiger sharks Our new research has revealed a 71% decline in tiger sharks across Queensland’s coastline (open-access version). In this blog I will explore the time-series modelling tech... [Read more...]

GLM tips: get non-linear with splines This tip is great for a quick non-linear test, before you go all the way with a GAM or parametric non-linear model. You’ll need the splines library, which comes shipped with R anyway. First, let’s make up a ... [Read more...]

R courses February 2020 Our next series of R courses for professionals and graduate students is now open for registration. The courses include 1-day for absolute beginners, 3 days for intermediate material and 3 days for the advanced class. They are r... [Read more...]

Diary of becoming a Bayesian Here’s my timeline of going from frequentist stats to becoming a fully fledged Bayesian eco-statistician. 2006 Read the Ecological Detective (Hilborn and Walters), the philosophy makes sense, the history of falsificatio... [Read more...]

R course in data wrangling and spatial analysis notes are online I have posted the notes to our new R course in data wrangling and spatial analysis notes on this webpage. The course is aimed at biological scientists who have some basic knowledge of R... [Read more...]

Generalized Linear Models: understanding the link function Generalized Linear Models (‘GLMs’) are one of the most useful modern statistical tools, because they can be applied to many different types of data. Count, binary ‘yes/no’, and waiting... [Read more...]

Beginner, Intermediate and Advanced R courses February 2019 This is an announcement of our next set of R courses. There are 4 separate courses taught over 5th-8th February 2019. You can register with the Centre for Applications in Resource Management... [Read more...]

Survey your audience and visualise the results with R and Google forms I wanted to make my presentation on dataviz at the UQ School of Bioinformatics more interactive. A quiz is a good way to engage your audience. Given I was giving a talk about R datavisuals I thought it ... [Read more...]

Data visuals 2018 Supplementary notes for CJ Brown’s talks on dataviz in 2018 for Griffith University’s honours students and the UQ Winterschool in Bioinformatics. These notes run through some of the principles I present and also show R code for generating data visuals. If you want to take the dataviz ... [Read more...]

How do I interpret the AIC? My student asked today how to interpret the AIC (Akaike’s Information Criteria) statistic for model selection. We ended up bashing out some R code to demonstrate how to calculate the AIC for a simple GLM (general linear model). I always think if you ... [Read more...]

Should I learn sf or sp for spatial R programming? I recently received an email about some of the short-courses on my webpage. The correspondant was asked whether my course on Maps and GIS in R was still relevant, it being written in 2014. The R env... [Read more...]