Large-sample analysis of cost functionals for inference under the coalescent

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Hauptverfasser: Favero, Martina, Koskela, Jere
Format: Preprint
Veröffentlicht: 2024
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author Favero, Martina
Koskela, Jere
author_facet Favero, Martina
Koskela, Jere
contents The coalescent is a foundational model of latent genealogical trees under neutral evolution, but suffers from intractable sampling probabilities. Methods for approximating these sampling probabilities either introduce bias or fail to scale to large sample sizes. We show that a class of cost functionals of the coalescent with recurrent mutation and a finite number of alleles converge to tractable processes in the infinite-sample limit. A particular choice of costs yields insight about importance sampling methods, which are a classical tool for coalescent sampling probability approximation. These insights reveal that the behaviour of coalescent importance sampling algorithms differs markedly from standard sequential importance samplers, with or without resampling. We conduct a simulation study to verify that our asymptotics are accurate for algorithms with finite (and moderate) sample sizes. Our results constitute the first theoretical description of large-sample importance sampling algorithms for the coalescent, provide heuristics for the a priori optimisation of computational effort, and identify settings where resampling is harmful for algorithm performance. We observe strikingly different behaviour for importance sampling methods under the infinite sites model of mutation, which is regarded as a good and more tractable approximation of finite alleles mutation in most respects.
format Preprint
id arxiv_https___arxiv_org_abs_2412_06004
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Large-sample analysis of cost functionals for inference under the coalescent
Favero, Martina
Koskela, Jere
Statistics Theory
Probability
Populations and Evolution
Computation
Primary 60J90, Secondary 62M05, 60F05, 92D15
The coalescent is a foundational model of latent genealogical trees under neutral evolution, but suffers from intractable sampling probabilities. Methods for approximating these sampling probabilities either introduce bias or fail to scale to large sample sizes. We show that a class of cost functionals of the coalescent with recurrent mutation and a finite number of alleles converge to tractable processes in the infinite-sample limit. A particular choice of costs yields insight about importance sampling methods, which are a classical tool for coalescent sampling probability approximation. These insights reveal that the behaviour of coalescent importance sampling algorithms differs markedly from standard sequential importance samplers, with or without resampling. We conduct a simulation study to verify that our asymptotics are accurate for algorithms with finite (and moderate) sample sizes. Our results constitute the first theoretical description of large-sample importance sampling algorithms for the coalescent, provide heuristics for the a priori optimisation of computational effort, and identify settings where resampling is harmful for algorithm performance. We observe strikingly different behaviour for importance sampling methods under the infinite sites model of mutation, which is regarded as a good and more tractable approximation of finite alleles mutation in most respects.
title Large-sample analysis of cost functionals for inference under the coalescent
topic Statistics Theory
Probability
Populations and Evolution
Computation
Primary 60J90, Secondary 62M05, 60F05, 92D15
url https://arxiv.org/abs/2412.06004