Multimodel approaches are not the best way to understand multifactorial systems

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Benjamin Bolker 


Information-theoretic (IT) and multi-model averaging (MMA) statistical approaches are widely used but suboptimal tools for pursuing a multifactorial approach (also known as the method of multiple working hypotheses) in ecology. (1) Conceptually, IT encourages ecologists to perform tests on sets of artificial models. (2) MMA improves on IT model selection by implementing a simple form of *shrinkage estimation* (a way to make accurate predictions from a model with many parameters, by "shrinking" parameter estimates toward zero). However, other shrinkage estimators such as penalized regression or Bayesian hierarchical models with regularizing priors are more computationally efficient and better supported theoretically. (3) In general the procedures for extracting confidence intervals from MMA are overconfident, giving overly narrow intervals. If researchers want to accurately estimate the strength of multiple competing ecological processes along with reliable confidence intervals, the current best approach is to use full (maximal) statistical models (possibly with Bayesian priors) after making principled, a priori decisions about which predictors to include.



Applied Statistics, Ecology and Evolutionary Biology


multi-model averaging, model selection, coverage, AIC, inference, shrinkage


Published: 2023-07-23 11:14

Last Updated: 2024-03-01 03:41

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