Patterns across 50 years of French presidential election

[Une version francaise de cette article est disponible ici] This year (2017) we will have our presidential election between April and May in France. A while ago I discovered the open data website of the French government publishing public data with free access and promoting utilization by anyone. So in this post I will explore … Continue reading Patterns across 50 years of French presidential election

Crossed and Nested hierarchical models with STAN and R

Below I will expand on previous posts on bayesian regression modelling using STAN (see previous instalments here, here, and here). Topic of the day is modelling crossed and nested design in hierarchical models using STAN in R. Crossed design appear when we have more than one grouping variable and when data are recorded for each … Continue reading Crossed and Nested hierarchical models with STAN and R

Hierarchical models with RStan (Part 1)

Real-world data sometime show complex structure that call for the use of special models. When data are organized in more than one level, hierarchical models are the most relevant tool for data analysis. One classic example is when you record student performance from different schools, you might decide to record student-level variables (age, ethnicity, social … Continue reading Hierarchical models with RStan (Part 1)

Simulating local community dynamics under ecological drift

In 2001 the book by Stephen Hubbell on the neutral theory of biodiversity was a major shift from classical community ecology. Before this book the niche-assembly framework was dominating the study of community dynamics. Very briefly under this framework local species composition is the result of the resource available at a particular site and species … Continue reading Simulating local community dynamics under ecological drift

Exploring the diversity of Life using Rvest and the Catalog of Life

I am writing the general introduction for my thesis and wanted to have a nice illustration of the diversity of Arthropods compared to other phyla (my work focus on Arthropods so this is a nice motivation). As the literature I have had access so far use pie charts to graphically represent these diversities and knowing … Continue reading Exploring the diversity of Life using Rvest and the Catalog of Life

Plotting regression curves with confidence intervals for LM, GLM and GLMM in R

[Updated 22nd January 2017, corrected mistakes for getting the fixed effect estimates of factor variables that need to be averaged out] Once models have been fitted and checked and re-checked comes the time to interpret them. The easiest way to do so is to plot the response variable versus the explanatory variables (I call them … Continue reading Plotting regression curves with confidence intervals for LM, GLM and GLMM in R

Count data: To Log or Not To Log

Count data are widely collected in ecology, for example when one count the number of birds or the number of flowers. These data follow naturally a Poisson or negative binomial distribution and are therefore sometime tricky to fit with standard LMs. A traditional approach has been to log-transform such data and then fit LMs to … Continue reading Count data: To Log or Not To Log