“…Building on the work of Gould () and Johnson & Wehrly (), Fisher & Lee () proposed models in which one or both of the mean direction and concentration parameters are related to covariates through a linear predictor and link function which maps the real line (the range of the linear predictor) to the appropriate range of the corresponding von Mises parameter ( i.e ., to (− π , π ) in the case of the mean direction and [0,∞) for the concentration). As pointed out by Presnell, Morrison & Littell (), however, there are serious drawbacks to this approach, including multimodality of the likelihood surface, non‐identifiability, and computational problems. Instead, these authors proposed a class of models based upon the angular normal distribution, which has a latent variable formulation, in which the observed angular response corresponds to the angle formed by an underlying latent multivariate normal random vector.…”