Week 5: Model Validation and Selection

At this point we know how to specify, execute, and interpret output from linear models. But how do we know if they’re even working?

This week we will focus on model specification - how to determine what covariates to include, and how to assess whether the model has fit your data well.

Lecture Topics

  • Model validation
  • Standardization of covariates
  • Variance Inflation Factor
  • Model selection

In-class Activities

As always, this class will have a mixture of R code and lecture slides

Pre-class Prep

Please read:

Zuur, A. F. and Ieno, E. N. (2016), A protocol for conducting and presenting results of regression-type analyses. Methods Ecol Evol, 7: 636–645. doi:10.1111/2041-210X.12577

Full comprehension is not expected at this stage.


Helpful resources

Diagnostic tools for linear regression

Schielzeth, H. (2010). Simple means to improve the interpretability of regression coefficients. Methods in Ecology and Evolution, 1(2), 103-113.

Johnson, J. B., & Omland, K. S. (2004). Model selection in ecology and evolution. Trends in Ecology & Evolution, 19(2), 101-108.

If you are interested in model averaging (which we won’t cover in this course)

Burnham, K. P., & Anderson, D. R. (2003). Model selection and multimodel inference: a practical information-theoretic approach. Springer Science & Business Media.

Information theoretic approach example

Fukuda Y, Manolis C, Saalfeld K, Zuur A (2015) Dead or Alive? Factors Affecting the Survival of Victims during Attacks by Saltwater Crocodiles (Crocodylus porosus) in Australia. PLoS ONE 10(5): e0126778. doi:10.1371/journal.pone.0126778




Slides available on Speakerdeck