Vecchia Approximations and Optimization for Multivariate Matérn Models
Volume 20, Issue 4 (2022): Special Issue: Large-Scale Spatial Data Science, pp. 475–492
Pub. online: 14 October 2022
Type: Computing In Data Science
Open Access
Received
1 August 2022
1 August 2022
Accepted
11 October 2022
11 October 2022
Published
14 October 2022
14 October 2022
Abstract
We describe our implementation of the multivariate Matérn model for multivariate spatial datasets, using Vecchia’s approximation and a Fisher scoring optimization algorithm. We consider various pararameterizations for the multivariate Matérn that have been proposed in the literature for ensuring model validity, as well as an unconstrained model. A strength of our study is that the code is tested on many real-world multivariate spatial datasets. We use it to study the effect of ordering and conditioning in Vecchia’s approximation and the restrictions imposed by the various parameterizations. We also consider a model in which co-located nuggets are correlated across components and find that forcing this cross-component nugget correlation to be zero can have a serious impact on the other model parameters, so we suggest allowing cross-component correlation in co-located nugget terms.
Supplementary material
Supplementary MaterialThe datasets and code used for this project can be found at https://github.com/yf297/GpGp_multi_paper.