Extreme Value Modelling of Water-related Insurance Claims

This paper considers the dependence between weather events, e.g., rainfall or snow-melt, and the number of water-related property insurance claims. Weather events which cause severe damages are of general interest, decision makers want to take efficient actions against them while the insurance companies want to set adequate premiums. The modelling is challenging since the underlying dynamics vary across geographical regions due to differences in topology, construction designs and climate. We develop new methodology to improve the existing models which fail to model high numbers of claims. The statistical framework is based on both mixture and extremal mixture modelling, with the latter being based on a discretized generalized Pareto distribution. Furthermore, we propose a temporal clustering algorithm and derive new covariates which lead to a better understanding of the association between claims and weather events. The modelling of the claims, conditional on the locally observed weather events, both fits the marginal distributions well and captures the spatial dependence between locations. Our methodology is applied to three cities across Norway to demonstrate its benefits.