Articles by Maxwell B. Joseph

Clarifying vague interactions

August 18, 2013 | Maxwell B. Joseph

For some reason, authors occasionally present linear model results with vague or unintelligible interaction effects. One way to be vague when presenting interaction effects is to provide only a table of model coefficients, including no information on the range of covariate values observed, and no plots to aid in interpretation. ... [Read more...]

Occupancy model fit & AUC

July 30, 2013 | Maxwell B. Joseph

Occupancy models are used to understand species distributions while accounting for imperfect detection. In this post, I’ll demonstrate a method to evaluate the performance of occupancy models based on the area under a receiver operating characteristic curve (AUC), as published last year by Elise Zipkin and colleagues in Ecological ... [Read more...]

Bayesian model II regression

May 27, 2013 | Maxwell B. Joseph

Regression is a mainstay of ecological and evolutionary data analysis. For example, a disease ecologist may use body size (e.g. a weight from a scale with measurement error) to predict infection. Classical linear regression assumes no error in covariates; they are known exactly. This is rarely the case in ... [Read more...]

Modeling habitat diversity and species richness

April 20, 2013 | Maxwell B. Joseph

How does habitat diversity affect species richness? Perhaps intuition suggests that habitat diversity increases species richness by facilitating niche or resource partitioning among species. But, for a fixed area, as habitat heterogeneity increases, the area that can be allocated to each habitat type decreases. In a recent paper, Allouche and ... [Read more...]

Dynamic community occupancy modeling with R and JAGS

February 24, 2013 | Maxwell B. Joseph

This post is intended to provide a simple example of how to construct and make inferences on a multi-species multi-year occupancy model using R, JAGS, and the ‘rjags’ package. This is not intended to be a standalone tutorial on dynamic community occupancy modeling. Useful primary literature references include MacKenzie et ... [Read more...]

Multi-species dynamic occupancy model with R and JAGS

February 24, 2013 | Maxwell B. Joseph

This post is intended to provide a simple example of how to construct and make inferences on a multi-species multi-year occupancy model using R, JAGS, and the ‘rjags’ package. This is not intended to be a standalone tutorial on dynamic community occupancy modeling. Useful primary literature references include MacKenzie et ... [Read more...]

Interactive two-host SIR model

February 20, 2013 | Maxwell B. Joseph

This is an example of interfacing R, shiny, and deSolve to produce an interactive environment where users can explore model behavior by altering parameters in an easy to use GUI. The model tracks the number of susceptible, infectious, and recovered individuals in two co-occuring host species. The rates of change ... [Read more...]

Interactive stage-structured population model

February 16, 2013 | Maxwell B. Joseph

This is an example of interfacing R and shiny to allow users to explore a biological model often encountered in an introductory ecology class. We are interested the growth of a population that is composed of multiple, discrete stages or age classes. Patrick H. Leslie provides an in-depth derivation of ... [Read more...]
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