Abstract: A trend analysis system accesses a database of values related to a plurality of events and a geographical map of a region of interest, the map including boundary divisions that represent a type of event. A user inputs a preliminary set of parameters to categorize the type of event and allows the trend analysis system to create assumptions related to the type of event, the assumptions being related to a spatial decay rate for the influence on a value of interest associated with each event. The trend analysis system determines an assumptions variable based upon the assumptions and prepares a density map based upon the assumptions variable, the type of event, the geographical map, the preliminary set and the database of values. The density map has large values in regions with a large numbers of events and small values in regions with a small number of events.