Statistics Seminar Series: Conditional Formulation of Gaussian Systems on Spatial Networks with Irregularly Distributed Points

Conditional Formulation of Gaussian Systems on Spatial Networks with Irregularly Distributed Points

Join the Department of Statistics for a seminar featuring Debashis Mondal, associate professor at the Department of Statistics, Oregon State University.

Abstract:

In this talk I develop a mathematical and statistical framework for analyzing spatial systems on irregularly distributed point locations. Using conditional formulations, this framework constructs Gaussian systems on spatial networks with symmetric weights for both stationary and non-stationary point processes. The framework associates these systems with reversible Markov chains and, through Kipnis--Varadhan invariance principles, establishes geostatistical scaling limits that recover the de Wijs process or Gaussian free field under stationary sampling and generalize to more complex limits under inhomogeneous sampling. The framework further studies convergence through Beurling--Deny decomposition, the effects of non-uniform sampling on limiting fields, and normalization procedures based on Hungarian embeddings, Sinkhorn normalization, and density correction for restoring canonical limits. It also enables scalable matrix-free computation, REML estimation, conditional simulation, spatial prediction, and sampling-invariant inference on large irregular spatial networks, for which there is currently little parallel in the geostatistical literature. The talk concludes with applications to mapping soil organic carbon in Tanzania, reconstructing global seawater oxygen isotope fields, and analyzing leukemia survival data from northwest England.

This seminar presents joint work with postdoctoral scholar Subhrajyoty Roy.

About the Speaker:

Debashis Mondal is an associate professor at the Department of Statistics, Oregon State University. Prior to joining Oregon State in 2014, Mondal was on the statistics faculty at the University of Chicago. He received his PhD. in statistics from the University of Washington and both his bachelor and master’s degrees in statistics from the Indian Statistical Institute in Kolkata, India.

Mondal's research interests include spatial statistics, MCMC and time series. He is a recipient of the NSF career award, the young researcher award by the International Indian Statistical Association, and is an elected member of the International Statistical Institute.