Publications by Sofia Charlotta Olhede

Related publications (13)

The Debiased Spatial Whittle likelihood

We provide a computationally and statistically efficient method for estimating the parameters of a stochastic covariance model observed on a regular spatial grid in any number of dimensions. Our proposed method, which we call the Debiased Spatial Whittle l ...

WILEY2022

Atomic subgraphs and the statistical mechanics of networks

Sofia Charlotta Olhede

We develop random graph models where graphs are generated by connecting not only pairs of vertices by edges, but also larger subsets of vertices by copies of small atomic subgraphs of arbitrary topology. This allows for the generation of graphs with extens ...

2021

Modeling Network Populations via Graph Distances

Sofia Charlotta Olhede

This article introduces a new class of models for multiple networks. The core idea is to parameterize a distribution on labeled graphs in terms of a Frechet mean graph (which depends on a user-specified choice of metric or graph distance) and a parameter t ...

AMER STATISTICAL ASSOC2021

Multivariate geometric anisotropic Cox processes

Sofia Charlotta Olhede

This paper introduces a new modeling and inference framework for multivariate and anisotropic point processes. Building on recent innovations in multivariate spatial statistics, we propose a new family of multivariate anisotropic random fields, and from th ...

WILEY2023

A developmental shift in habituation to pain in human neonates

Sofia Charlotta Olhede

Habituation to recurrent non-threatening or unavoidable noxious stimuli is an important aspect of adaptation to pain. Neonates, especially if preterm, are exposed to repeated noxious procedures during their clinical care. They can mount strong behavioral, ...

CELL PRESS2023

The elliptical Ornstein-Uhlenbeck process

Sofia Charlotta Olhede

We introduce the elliptical Ornstein-Uhlenbeck (OU) process, which is a generalisation of the well-known univariate OU process to bivariate time series. This process maps out elliptical stochastic oscillations over time in the complex plane, which are obse ...

INT PRESS BOSTON, INC2023

What is the Fourier Transform of a Spatial Point Process?

Sofia Charlotta Olhede

This paper determines how to define a discretely implemented Fourier transform when analysing an observed spatial point process. To develop this transform we answer four questions; first what is the natural definition of a Fourier transform, and what are i ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2023

Tractably modelling dependence in networks beyond exchangeability

Sofia Charlotta Olhede

We propose a general framework for modelling network data that is designed to describe aspects of non-exchangeability, with an explicit parameter describing the degree of non-exchangeability. Conditional on latent (unobserved) variables, the edges of the n ...

2025

Testing for Equivalence of Network Distribution Using Subgraph Counts

Sofia Charlotta Olhede

We consider that a network is an observation, and a collection of observed networks forms a sample. In this setting, we provide methods to test whether all observations in a network sample are drawn from a specified model. We achieve this by deriving the j ...

AMER STATISTICAL ASSOC2020

Networks with correlated edge processes

Mária Süveges, Sofia Charlotta Olhede

This article proposes methods to model non-stationary temporal graph processes motivated by a hospital interaction data set. This corresponds to modelling the observation of edge variables indicating interactions between pairs of nodes exhibiting dependenc ...

OXFORD UNIV PRESS2023

Nonparametric inference of higher order interaction patterns in networks

Sofia Charlotta Olhede

Local interaction patterns play an important role in the structural and functional organization of complex networks. Here we propose a method for obtaining parsimonious decompositions of networks into higher order interactions which can take the form of ar ...

2024

Local linear graphon estimation using covariates

Sofia Charlotta Olhede

We consider local linear estimation of the graphon function, which determines probabilities of pairwise edges between nodes in an unlabelled network. Real-world networks are typically characterized by node heterogeneity, with different nodes exhibiting dif ...

OXFORD UNIV PRESS2022

Can smooth graphons in several dimensions be represented by smooth graphons on [0, 1]?

Sofia Charlotta Olhede

A graphon that is defined on [0, 1]d and is H & ouml;lder(a) continuous for some d 2 and a is an element of (0, 1] can be represented by a graphon on [0, 1] that is H & ouml;lder(a/d) continuous. We give examples that show that this reduction in smoothness ...

ELSEVIER2021