🤖 AI Summary
Existing methods struggle to effectively identify spatial clusters in categorical functional data. This work proposes a novel spatial scan statistic that, for the first time, integrates an encoding mechanism for categorical functional data with a nonparametric scan statistic to detect clustering patterns in complex spatiotemporal datasets. The method demonstrates high true positive rates, low false positive rates, and high positive predictive values in simulation studies. It was successfully applied to winter 2024 air pollution data from France, effectively uncovering the spatial clustering structure of pollution events. This approach establishes a new paradigm for spatial analysis of categorical functional data.
📝 Abstract
We have developed and tested a spatial scan statistic for categorical, functional data (CFSS) - a data structure within which current approaches cannot identify spatial clusters. Our methodology combines an encoding scheme for categorical, functional observations with a nonparametric scan statistic. In a simulation study with three distinct scenarios, the CFSS accurately recovered the simulated spatial clusters and gave very low false positive rates, high true positive rates, and high positive predictive values. We have also used the CFSS to identify and characterize spatial clusters in French air pollution data from the winter of 2024.