How close is a complex movement model to reality? Jonathan Potts, Marie Auger-Méthé, Karl Morkoss, Mark Lewis

Some history

One outcome: Often conclusions are made based on relative fit between models How about absolute fit?

One outcome: Often conclusions are made based on relative fit between models How about absolute fit? Suggestion: look at the residuals in step-length and turning angle distributions

How do we extend the idea of a residual to more complex movement models?

Study species

e.g. food distribution e.g. topography Actual move

Earth mover`s distance: a generalised residual

Standardised earth mover`s distance

How close is your model to the data? Test the following null hypothesis: H 0 : “The data is indistinguishable from a stochastic realisation of the model”

Power test on simulated data C(x) T(x) Researcher knows about layer 1 Researcher doesn’t know about layer 2

Power test on simulated data C(x) T(x) Researcher knows about layer 1 Researcher doesn’t know about layer 2

Power test on simulated data Potts JR, Auger-Méthé M, Mokross K, Lewis MA. A generalized residual technique for analyzing complex movement models using earth mover's distance. Methods Ecol Evol DOI: / X.12253A generalized residual technique for analyzing complex movement models using earth mover's distance

Where is my model failing? Patterns in EMD

Acknowledgements Mark Lewis (Alberta) Marie Auger-Méthé (Dalhousie) Karl Mokross (Louisiana State)

Conclusion Want to know how good your model is in an absolute rather than relative sense?

Conclusion Want to know how good your model is in an absolute rather than relative sense? Use EMD for the best results. EMD