Flexible unimodal density estimation in hidden Markov models

Fuente: arXiv
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Hauptverfasser: Koslik, Jan-Ole, Dupont, Fanny, Auger-Méthé, Marie, Marcoux, Marianne, Hussey, Nigel, Heckman, Nancy
Format: Preprint
Veröffentlicht: 2025
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author Koslik, Jan-Ole
Dupont, Fanny
Auger-Méthé, Marie
Marcoux, Marianne
Hussey, Nigel
Heckman, Nancy
author_facet Koslik, Jan-Ole
Dupont, Fanny
Auger-Méthé, Marie
Marcoux, Marianne
Hussey, Nigel
Heckman, Nancy
contents 1. Hidden Markov models (HMMs) are powerful tools for modelling time-series data with underlying state structure. However, selecting appropriate parametric forms for the state-dependent distributions is often challenging and can lead to model misspecification. To address this, P-spline-based nonparametric estimation of state-dependent densities has been proposed. While offering great flexibility, these approaches can result in overly complex densities (e.g. bimodal) that hinder interpretability. 2. We propose a straightforward method that builds on shape-constrained spline theory to enforce unimodality in the estimated state-dependent densities through enforcing unimodality of the spline coefficients. This constraint strikes a practical balance between model flexibility, interpretability, and parsimony. 3. Through two simulation studies and a real-world case study using narwhal (Monodon monoceros) dive data, we demonstrate the proposed approach yields more stable estimates compared to fully flexible, unconstrained models improving model performance and interpretability. 4. Our method bridges a key methodological gap, by providing a parsimonious HMM framework that balances the interpretability of parametric models with the flexibility of nonparametric estimation. This provides ecologists with a powerful tool to derive ecologically meaningful inference from telemetry data while avoiding the pitfalls of overly complex models.
format Preprint
id arxiv_https___arxiv_org_abs_2511_17071
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Flexible unimodal density estimation in hidden Markov models
Koslik, Jan-Ole
Dupont, Fanny
Auger-Méthé, Marie
Marcoux, Marianne
Hussey, Nigel
Heckman, Nancy
Methodology
Applications
1. Hidden Markov models (HMMs) are powerful tools for modelling time-series data with underlying state structure. However, selecting appropriate parametric forms for the state-dependent distributions is often challenging and can lead to model misspecification. To address this, P-spline-based nonparametric estimation of state-dependent densities has been proposed. While offering great flexibility, these approaches can result in overly complex densities (e.g. bimodal) that hinder interpretability. 2. We propose a straightforward method that builds on shape-constrained spline theory to enforce unimodality in the estimated state-dependent densities through enforcing unimodality of the spline coefficients. This constraint strikes a practical balance between model flexibility, interpretability, and parsimony. 3. Through two simulation studies and a real-world case study using narwhal (Monodon monoceros) dive data, we demonstrate the proposed approach yields more stable estimates compared to fully flexible, unconstrained models improving model performance and interpretability. 4. Our method bridges a key methodological gap, by providing a parsimonious HMM framework that balances the interpretability of parametric models with the flexibility of nonparametric estimation. This provides ecologists with a powerful tool to derive ecologically meaningful inference from telemetry data while avoiding the pitfalls of overly complex models.
title Flexible unimodal density estimation in hidden Markov models
topic Methodology
Applications
url https://arxiv.org/abs/2511.17071