Ameijeiras Alonso, JoséGijbels, Irène2026-03-262026-03-262025Ameijeiras-Alonso, J., & Gijbels, I. (2025) Semiparametric regression for circular responsewith application in ecology. Scandinavian Journal of Statistics, 53(1), 54-101. https://doi.org/10.1111/sjos.70027https://hdl.handle.net/10347/46536A regression model for a circular response variabledepending on a linear or a circular predictor is pre-sented in this paper. The conditional density belongsto a parametric flexible family that allows for asymme-try and varying peakedness around the modal direction.The modal direction and concentration depend on thecovariate and are nonparametrically modeled via localpolynomial fitting with a kernel weight. The asymp-totic normality of the estimators for the conditionalmodal direction and concentration is established. Fur-thermore, from these theoretical results, the expressionof the optimal smoothing parameter and a proposeddata-driven estimator are derived. An application con-cerns the orientation of migratory birds according to theflight altitude and the wind direction.engThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use,distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2025 The Author(s). Scandinavian Journal of Statistics published by John Wiley & Sons Ltd on behalf of The Board of the Foundation ofthe Scandinavian Journal of Statistics.Attribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/Directional statisticsFlexible modelingLocal likelihoodModal direction regressionjournal article10.1111/sjos.700271467-9469open access