A random-effects model for clustered circular data

This article considers a circular regression model for clustered data, where both the cluster effects and the regression errors have von Mises distributions. It involves beta, a vector of parameters for the fixed effects, and two concentration parameters for the error distribution. A measure of intra-cluster circular correlation and a predictor for an unobserved cluster random effect are studied. Preliminary estimators for the vector beta and the two concentration parameters are proposed, and their performance is compared with that of the maximum likelihood estimators in a simulation study. A numerical example investigating the factors impacting the orientation taken by a sand hopper when released is presented. The Canadian Journal of Statistics 00: 000-000; 2019 (c) 2019 Statistical Society of Canada