A generalized residual technique for analyzing complex movement models using earth mover's distance
Jonathan R. PottsMarie Auger-MéthéKarl MokrossMark A. Lewis
所有作者
Jonathan R. PottsMarie Auger-MéthéKarl MokrossMark A. Lewis
文献摘要
Complex systems of moving and interacting objects are ubiquitous in the
natural and social sciences. Predicting their behavior often requires models
that mimic these systems with sufficient accuracy, while accounting for their
inherent stochasticity. Though tools exist to determine which of a set of
candidate models is best relative to the others, there is currently no generic
goodness-of-fit framework for testing how close the best model is to the real
complex stochastic system.
We propose such a framework, using a novel application of the Earth
mover’s distance, also known as the Wasserstein metric. It is applicable to any
stochastic process where the probability of the model’s state at time t is a
function of the state at previous times. It generalizes the concept of a
residual, often used to analyze 1D summary statistics, to situations where the
complexity of the underlying model’s probability distribution makes standard
residual analysis too imprecise for practical use.
We give a scheme for testing the hypothesis that a model is an accurate
description of a data set. We demonstrate the tractability and usefulness of
our approach by application to animal movement models in complex, heterogeneous
environments. We detail methods for visualizing results and extracting a
variety of information on a given model’s quality, such as whether there is any
inherent bias in the model, or in which situations it is most accurate. We
demonstrate our techniques by application to data on multi-species flocks of
insectivore birds in the Amazon rainforest.
This work provides a usable toolkit to assess the quality of generic
movement models of complex systems, in an absolute rather than a relative
sense.